[Apologies in advance if I sound like I'm over-generalizing high-conscientiousness or low-conscientiousness people. This is mostly from my own experience, so I'm sure I'm wrong on some counts and may, in fact, be over-generalizing at times. Ohh, and also apologies to Mick Jaggar.]

Please allow me to introduce myself. I'm a man of mess and wile. I've been scoring around 20% (in trait conscientiousness on Big Five tests) for a long, long year, cut by many a sharp wire’s height.

At first glance, conscientiousness as a construct seems a bit like intelligence, in the sense that it would seem everyone would be better off with more of it. So, why would natural selection produce people like me who are very low in conscientiousness? Have I only escaped a Darwin award by the grace of the almighty simulator?

I have a hypothesis that low-conscientiousness people may function a bit like dichromats (color blind people) on teams of hunter-gathers. While dichromats can't see some colors, they can detect color-camouflaged objects better than non-color blind people (trichromats). So, teams with mixtures of dichromats and trichromats may have out-competed teams with only trichromats (or only dichromats, for that matter).   

Perhaps some diversity of conscientiousness in groups could produce a competitive advantage? There is some evidence in this direction. Just from skimming Wikipedia:

• The world's most conscientious nations are also some of the poorest.
• Groups with only conscientious members have difficulty solving open-ended problems.
• Those scoring low on conscientiousness make better decisions after unanticipated changes in the context of a task.
• Conscientiousness has been found to be positively correlated with business and white-collar crime.

But, specifically, I'd like to surface patterns I've observed in my own experience that I haven't seen discussed elsewhere. I work with, and am related to, many high-conscientiousness people. I've come to appreciate their strengths relative to mine, but I also have first-hand experience with some failure modes of conscientiousness taken too far. Any virtue taken to an extreme can become a vice, as Dieter said. (No, not that Dieter, Dieter Uchtdorf). 
 

Allow me to present four of my observed failure modes of high-consciousness.
 

#1 Not all messes are worth the risk of cleaning them up

This is the most frequent failure mode I see amongst high-conscientiousness people I work with. In lieu of a technical example, let me give you a more practical one. 

I live in a fairly old neighborhood. Houses are typically made of brick, and I'd estimate the mean age of a house in my neighborhood is about 85 years old. Brick and mortar tend to get crumbly in spots over time. Often to keep structural integrity you need to repoint the mortar and/or replace damaged brick. Though, if you haven’t poked at your exterior brick walls or had sufficient experience with deteriorating brick and mortar, you probably wouldn’t be aware of this.

Last summer, I overhead a conversation between two neighbors that could have entered this failure mode, but likely narrowly avoided it. We'll call my neighbors Charlotte and Miranda. 

Conscientious Charlotte has an old brick garage that used to have ivy growing on three sides, though she recently removed it from the south side. Removing the ivy left a lot of unsightly "rootlets" on the brick surface of the south side exterior. Charlotte told Miranda that the rootlets look messy and that she'd like to clean them off. 

Miranda says her spouse has a pressure washer that may help. Miranda goes home and asks her spouse, Marla, if Charlotte can barrow the power washer. Marla asks "what for?" and Miranda explains Charlotte's predicament. Marla says, "Sure she can borrow it, just let her know that depending on how weathered the brick and mortar is, she may not have a garage standing when she's done power washing the rootlets off." (Marla was completely right, see item #06 here).

A defender of high-conscientiousness could retort here and say “Charlotte's problem wasn't conscientiousness, it was that she wasn't conscientiousness enough.“ I believe this is confusing conscientiousness with circumspection. Circumspection requires some amount of curiosity, which is associated with trait openness. Maybe also  some worrying about what could go wrong, which seems like trait neuroticism.

My experience is more that the compulsion to clean up unfamiliar messes among high-conscientiousness people I work with tends to override any thoughtfulness regarding how to account for the unfamiliarity. Routine clean up is fine because it's routine. But when faced with a messy situation they haven't specifically encountered before it seems like their instinct is to address it through cleaning, organizing, sorting, ordering, adding structure, etc. rather than to to step back and say "how can we be sure we’re safely addressing this, or is it even worth the risk of addressing at all?" 

Low-conscientiousness people are likely to ask questions like this because we're naturally more adverse to cleaning up messes and, hence, only do it when it's really necessary or when we're coerced to. We'll wonder "is this worth my time?" Or "is this worth my team’s time?" If you’re lucky enough to have a low-conscientiousness team member that’s also high in openness and neuroticism, that may be even better here.

#2 Honestly estimate ROI before micro-optimization (avoid bikeshedding)

So, let's imagine Charlotte still wants to clean the rootlets off her garage. She now realizes she can't safely use a power washer unless she also wants to risk restoring or replacing her garage.

So she carefully goes out with a brush, a bucket of water and detergent, then she proceeds to clean rootlets one small section at a time. 

Look, it's Charlotte’s life and it’s her garage. If she wants to toothbrush rootlets off her garage exterior… it’s a free country (assuming you’re reading this in a free country).

I will argue a different calculus applies if you're doing something analogous in a work environment where you're billing a customer who expects value for their dollars, or someone is paying your salary who expects value from your work, or, importantly, if you're asking someone like me to do this when I could be working on something else.

Even after you’ve established a safe method for cleaning up a mess, is it really worth doing in comparison to all the other things you or someone else could be working on?

Situations like this are sometimes called bikeshedding. The term comes from a hypothetical project to build a nuclear power plant. In the midst of all of the planning necessary to safely build the plant, during a project meeting someone raises their hand and says “we should have a bike shed in case employees want to bike to work, and it should be green because we’re about green energy!” Then another person in the meeting says “No, it should be white to reflect more of the suns heat and maintain a lower temperature!” The meeting then spends an inordinate amount of time discussing what color the bike shed should be. The point being a relatively trivial matter derails the larger, more important discussion.

You may think conscientious people are good at avoiding this, my experience is the opposite. Sometimes small details are meaningful, sometimes they’re bikesheds, or rootlets on the garage. Honestly think about the ROI before micro-optimizing in these ways.

Low-conscientiousness people can, again, help here. We're not going to go around toothbrushing rootlets and we're less likely to care about details unless there's a strong argument in favor of their importance. 

#3 Avoid supererogation

Supererogation is doing more of something than required. One way to think about it is to imagine someone who commits a crime and gets sentenced to prison for 19 years, then when their 19 year sentence has expired they beg the prison guards to keep then for another 3 years so they can do even more penitence. If you're a Les Misérables fan, imagine Javert releasing Jean Valjean from prison to parole, only to find that Jean Valjean first protests that he hasn’t served enough time, then later complains that the parole terms are too lenient.

This is obviously a bit different than the Wikipedia definition, which describes more in the terms of doing more than what duty requires. But I maintain that those are apt analogies, if hyperbolic by comparison to more day-to-day examples.

(BEGIN SPOILER ALERT)

The straightforward and obvious example of supererogation from Les Misérables is Javert. In fact, Javert is more than an example of supererogation, he’s an example of terminal supererogation. You will often hear people say “follow the spirit of the law, not the letter of the law.” Javert is such a stan for law and duty, he makes anyone strictly following the letter of the law seem eminently reasonable by comparison. Without summarizing the plot, he tracks Valjean over the course of two decades and observes him not just obeying the law, but saving lives and taking care of others, but still wants to return him to prison. Not to get too dark, but Javert commits suicide after unsuccessfully grappling with his predicament.

This is similar to bikeshedding in that the ROI here, relative to other crimes and criminals, is low. (So low that it’s negative—it’s worse than quixotic. Arresting or executing Valjean at any point where Javert encounters him outside of prison would be a net harm to society.) It’s different than bikeshedding as the ROI is a known quantity but still is pursued for philosophical reasons—duty, law, etc. To say nothing of the loss of opportunity Javert trades to continue to pursue Valjean, not to mention the years of life he lost from ending it early.

(END SPOILER ALERT)

If you’re a Javert, a fraction of a Javert, or have such people on your team, maybe add some trusted low-conscientiousness people to help you chill things out a bit? Just stay away from Sacha Baron Cohen’s Inn.

#4 Beware the Superman complex

The Wikipedia definition of the Superman complex is pretty good. 

[An] unhealthy sense of responsibility, or the belief that everyone else lacks the capacity to successfully perform one or more tasks. Such a person may feel a constant need to "save" others and, in the process, takes on more work on their own.

It's different than someone who has a lot of responsibility thrust upon them, or who creates catastrophes to save things and get recognition.

I suspect we all know people who have played this role for parts of their lives. I won’t say this is limited to high-conscientiousness types, but I do see it frequently among many of the ones I know.

I don’t know if there’s deeper, psychoanalytic, reasons why people do this. But I would hope it’s a bit like removing your hand from a hot stove—once you recognize it, you can stop doing it.

Low-conscientiousness types may not be able to analyze the distal reasons for people doing this, but I’m pretty sure we’ll be better than others at spotting when you’re working to your own detriment and potentially the detriment of others.

The general pattern 

Apply the principle of maximum parsimony to all things "conscientiousness." With rules, for example, instead of more rules prefer the most parsimonious set of rules—the fewest rules necessary for the maximal outcome.