A while back I built something exactly like this (except it asked every 15 minutes, and as a desktop app that could unobtrusively pop up in the corner of a moni

A while back I built something exactly like this (except it asked every 15 minutes, and as a desktop app that could unobtrusively pop up in the corner of a monitor instead of requiring browser attention). It also asked what I expected to accomplish in the next 15 minutes, so I'd have something to look back on 15 minutes from now to compare to. At least for me, it was more an exercise in focus, breaking tasks down to smaller chunks, practicing estimations, and analyzing larger spans of time, rather than just being a tool to force me into actually working through those 15 minute segments. It was really nice to have a bit of self-reflection imposed every 15 minutes to see how my expectations of time use were stacking up against the reality. I don't think I would have wanted to spend the time or cognitive effort to revisit screenshots after the fact, when I've lost context and would have to take more time to analyze what's happening in each screenshot and extrapolate between them. If I were in the zone and working on something that took longer than 15 minutes (which is pretty frequent for most people, I'd guess), I could see this format as pretty nagging and I wouldn't want the interruption. But there's also a reason I only do 15-minute pomodoro sprints. :)