That's exactly why I've never tried it. I haven't found many situations where I can clock in at a specific time and clock out a few minutes later. 15 minutes, 2

That's exactly why I've never tried it. I haven't found many situations where I can clock in at a specific time and clock out a few minutes later. 15 minutes, 25 minutes, however long that clock is set for, what if I haven't even started to grasp the problem? And then I have to reset my mind? Again, I haven't even tried it, but my technique usually consists of "start working on a problem, stop working when you need a break". Works pretty well, and there's no timer involved.