The main example I can think of is realizing "hm, the amount of time I spend on X is very different from normal." For example, in Nick Winter's recent book he mentions that after he started timing his showers, he was able to take them in less than 2 minutes. I had no reference point for that- I wasn't even sure how long my showers took- and it happened that I normally spent about 20 minutes in the shower, and fairly quickly was able to get it down to 5 minutes.
I don't think that's a particularly compelling example, though, and don't expect that I would personally use this repository. (I stopped timing my showers and trying to make them shorter when I realized they were a major source of physical pleasure in my life, and making them shorter and more stressful was a terrible idea for me. Someone who doesn't enjoy taking a shower as much would probably gain from applying that time to something else.)
Yes. And people have been having fruitful insights while bathing since the time of Archimedes. Surely it's worth spending a little heat and water to have time to think?
Related: Repository Repository
It would be cool if we had a repository for the Outside/calibrated view for how long commonplace tasks take. This way we can help one another get around the planning fallacy to a certain degree. Nothing beats direct measurement, but we can possibly save energy if enough evidence comes in to make us suspect that the time a certain task takes doesn't vary.
I could update this thread as more contribute. Depending on the variety of tasks, categories could be created and an index can be compiled. Observe.
Chores
Washing Dishes: 30 mins
Doing Laundry: 1 hour including drying
Rationality
Average LessWrong Post: 3 minutes
"Mysterious Answers to Mysterious Questions": 4 hours
Misc.
...: ...
... and so on.