I think there are some serious low hanging fruits for making people productive that I haven't seen anyone write about (not that I've looked very hard). Let me just introduce a proof of concept:

Final exams in university are typically about 3 hours long. And many people are able to do multiple finals in a single day, performing well on all of them. During a final exam, I notice that I am substantially more productive than usual. I make sure that every minute counts: I double check everything and think deeply about each problem, making sure not to cut corners unless absolutely required because of time constraints. Also, if I start daydreaming, then I am able to immediately notice that I'm doing so and cut it out. I also believe that this is the experience of most other students in university who care even a little bit about their grade.

Therefore, it seems like we have an example of an activity that can just automatically produce deep work. I can think of a few reasons why final exams would bring out the best of our productivity:

1. We care about our grade in the course, and the few hours in that room are the most impactful to our grade.

2. We are in an environment where distractions are explicitly prohibited, so we can't make excuses to ourselves about why we need to check Facebook or whatever.

3. There is a clock at the front of the room which makes us feel like time is limited. We can't just sit there doing nothing because then time will just slip away.

4. Every problem you do well on benefits you by a little bit, meaning that there's a gradient of success rather than a binary pass or fail (though sometimes it's binary). This means that we care a lot about optimizing every second because we can always do slightly better.

If we wanted to do deep work for some other desired task, all four of these reasons seem like they could be replicable. Here is one idea (related to my own studying), although I'm sure I can come up with a better one if I thought deeply about this for longer:

Set up a room where you are given a limited amount of resources (say, a few academic papers, a computer without an internet connection, and a textbook). Set aside a four hour window where you're not allowed to leave the room except to go to the bathroom (and some person explicitly checks in on you like twice to see whether you are doing what you say you are doing). Make it your goal to write a blog post explaining some technical concept. Afterwards, the blog post gets posted to Lesswrong (conditional on it being at least minimal quality). You set some goal, like it must acheive 30 upvote reputation after 3 days. Commit to paying $1 to a friend for each upvote you score below the target reputation. So, if your blog post is at +15, you must pay $15 to your friend.

I can see a few problems with this design:

1. You are optimizing for upvotes, not clarity or understanding. The two might be correlated but at the very least there's a Goodhart effect.

2. Your "friend" could downvote the post. It can easily be hacked by other people who are interested, and it encourages vote manipulation etc.

Still, I think that I might be on the right track towards something that boosts productivity by a lot.