Ask HN: What to do when Claude Code is writing code?

I have been using claude code extensively for coding at my startup, but I am feeling that I can be more productive by utilising the time when the claude code is writing code instead of just staring what claude is doing.

One may think that it's a marginal time, but I have timed it, it's 2.5-3 hours per day split over 1/2 minutes window over the whole day.

Since the time window is short, I want something that I can complete in that time window. I have been solving chess puzzles during that time, but want to do something which benefits my startup in the long run, maybe learn something new.

How are you utilising that time?