I tend to favor your own approach—think about whatever I’m working on.
The solution to not having enough questions is to always keep a question around which is A: hard enough that you’re unlikely to solve it during a brief wait, and B: in a state where you can work on it without something to write on. Combining these two is not always easy, so you sometimes need to plan ahead.
Departing a bit from the question as stated, adding a phone(and headphones), I’ve also found that listening to audiobooks is a good way to use e.g. a commute.
I tend to favor your own approach—think about whatever I’m working on. The solution to not having enough questions is to always keep a question around which is A: hard enough that you’re unlikely to solve it during a brief wait, and B: in a state where you can work on it without something to write on. Combining these two is not always easy, so you sometimes need to plan ahead.
Departing a bit from the question as stated, adding a phone(and headphones), I’ve also found that listening to audiobooks is a good way to use e.g. a commute.