In the normal course of my rationalist upbringing, I learned about the classic cognitive biases, including the planning fallacy. This is essentially the fact that it almost always takes longer for a task to get done than people estimate at the beginning. The explanation described in the original sequence post is that people visualize the mainline path of accomplishing the steps of the task, and then just add those times together, whereas in reality, at least one of those steps will have something go wrong, and make the whole thing take much longer.
So I read this, and then just... updated? Typically one should be very skeptical about the feeling that they are not subject to a bias, but as discussed in the original sequence post, this one is empirically reported to be correctable. And I'm sure it took me some time to adjust, but it wasn't too difficult to install a TAP to just consult the outside view instead of the inside view.
And then I went forth into the world, and gave calibrated time estimates, because I want to have true beliefs and I want to say true things. Slowly, over time, I got the sinking sense that this was costing me social points.
Types of costs
People may think you're slow
A primary context in which I had to give time estimates was when working as a software engineer. I've worked at multiple companies that regularly used "sprints" to plan work, and we often assigned explicit estimates to the tasks at hand. I regularly gave longer estimates than my coworkers or manager. These estimates were also calibrated; I actually took about that long. Sometimes more, sometimes less. My coworkers usually took longer than their estimates, but their estimates were shorter.
Over time, I believe my managers got a worse impression of me. One simple problem here is that shorter estimates just sound better than longer estimates because the manager wants the thing done sooner. But another slightly subtler problem is that since almost everyone gives optimistic estimates, my manager would reasonably be used to hearing optimistic estimates. So if they hear me give a longer estimate, they don't know that it's more calibrated, so they subconsciously assume it's just as optimistic as my coworkers, and then they would reasonably believe that I am worse.
Ideally, my calibration would eventually be evident through cumulative statistics. But realistically, people aren't paying attention on this level. They regularly feel the short-term displeasure of longer estimates, and they only irregularly get the pleasure from noticing that I finished it earlier than I said, and it's hard to connect up these two signals that are days or weeks apart.
People may think you're lazy
Claiming that things will take longer also just sounds like you're trying less hard. If Jane says she can get this done in a day, why can't you? Are you saying she's lying? Maybe you're just not trying as hard.
People dislike pessimism
Saying that something will take longer is negative-valence. You are claiming that the world is worse, and hearing that feels bad. People don't like regulations and safety expectations, because in the short term they are annoying and costly, even though in the long term they are designed to be much better for you. Hearing someone say that something will take longer is annoying and costly in the short term, even though being calibrated could allow the whole project to plan better.
People can feel insulted
The planning fallacy also applies to other people telling me their time estimates. I have no reason to assume other people are calibrated, and in my experience they usually do take longer than they estimate. And yet, telling them that you think their estimate is too short is rarely going to be taken well. Often I can just hear their estimate, not say anything, and then personally assume and prepare for it to take much longer. But that's not always an option, for example if you're working together on the task, or if you care about helping the person plan better
People want commitment
In a related problem, sometimes people will ask me "can you get this done by [time]?" and I'll say something like "seems reasonable" but as the discussion carries on, it becomes clear that they want me to basically *promise* that I'll get the task done by then. My problem with this has two parts. One is that my priors on how long it takes to do things in general are not just later than others, but also very wide. There just is a good chance that things will take *much* longer.
The second part is that, for me to utter a statement X, I have to believe it with a certain probability that is fairly high. So when someone wants me to echo back the unqualified statement "I will get it done by [time]", they're basically asking me to be, I dunno, 98% confident, and I just can't be, because I know that the 98th percentile time is actually more like 3*[time]. So I continue to hedge, and then if they push I basically tell them the above, and then they feel like I'm making a point to not commit, and then maybe they start thinking the above things, like that I'm slow or lazy or something.
The annoying thing here is that I believe the only difference between me and another task doer in this situation is that I have more accurate beliefs, or I have a higher belief threshold for making claims (or something similar, like that I only use statements for communicating beliefs and not for socially enforcing a commitment to myself). I think I can get the thing done just as fast as someone else, and thus I think I can satisfy the task-giver just as much, but they currently feel less satisfied because of the above communication.
Being out of sync with others
The last type of cost I can think of is when me and someone else are both equal parties subject to something else getting done. Say that me, Jane and Jack are going to the movies. I know that Jack always takes a long time to get ready at the last minute, and so I am psychologically prepared for this. We show up at Jack's house, and I go ahead and sit down on the couch and start reading on my phone. Maybe we'll miss the first few minutes of the movie, or get worse seats or something, but I've already accepted that as a likely consequence of going to the movies with Jack. Jane however has not done the same level of planning fallacy compensation as me, and so Jane feels surprised and frustrated when Jack takes a long time. This isn't exactly a conflict between me and Jane, but it can be awkward. Maybe Jane is anxiously pacing around while I'm relaxing on the couch. Maybe she feels like I should be on her side by feeling equally impatient, or something. Maybe she feels like I'm enabling Jack by not demonstrating urgency.
An example that did happen to me is that my house is having its electrical system replaced. This is taking a very, very, very long time. Many of my roommates seem not just annoyed (which anyone reasonably would be) but also something like surprised by this. And, I dunno, I just knew it would take forever and ever? I just decided to start living my life as if it would never end. I remember literally thinking to myself, "it would be nice if this got finished in 2021". I currently have my fingers crossed for it being finished in 2022.
And again, this isn't exactly a conflict between me and my roommates, but I feel a little bit snobbish just for even writing the above sentences. And I think that difference can seed some kind of low-key tension after enough repetitions.
Mostly my solution to the above is to just remember that they happen, and add that in to the social calculus that I'm always running every time I interact with a person. Often I just pay the social costs, partly because I have pretty high social resilience, partly because I continue to want to be a person that acts from my beliefs even when it's costly. (The solution of "just give shorter time estimates" is basically a non-starter for me.) The adjustments I do make are usually in the form of giving the estimate with softer wording, some kind of hedging, or just being more clear about my intention versus my uncertainty. I'm pretty sure that a more socially skilled person than me would have clearly communicable solutions that used some kind of charisma warmth to make the listener feel better despite the longer estimate.
Here and elsewhere, feel free to just, like, not believe my self-reports. I do not in fact have the data handy in spreadsheets, or anything.
To be totally fair, there were also times when I was actually worse than my coworkers. But this problem compounded the impression during those times.