I agree that all of these measures help greatly, in particular with bigger problems. Nevertheless, I found that in the end, even when you've broken up a problem

I agree that all of these measures help greatly, in particular with bigger problems. Nevertheless, I found that in the end, even when you've broken up a problem into chunks, keeping your focus on these connected chunks for an uninterrupted extended time period is invaluable. Often your realise that you should reorganise the chunk division etc. Of course you also benefit from breaks of looking at the problem, but these breaks tend to occur naturally for me, and are very different from a forced break of having to tend to another project. Or let's put it another way: I don't multitask / switch contexts.