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.

Pomodoro designed to solve procrastination issues, when you're spending time watching cats on youtube instead of starting to work. If you have no problems starting to work, you don't need pomodoro, just do your work.

There are trade offs to using pomodoro, but I find it's worth it. I get more work done with it than without it even taking into consideration distraction and switching costs.

I might be annoyed to be interrupted when I'm in the zone, but I don't procrastinate or lose focus during work intervals — being interrupted every 25 minutes is better than spending those 25 minutes scrolling through Reddit or HN.

Also, if a session ends and I'm really focused, I just ignore it and carry on working. Pomodoro is a framework, not a straitjacket.