Agreed. A large amount of time also goes into things like making figures, which is mostly time-consuming grunt work. I think the key is differentiating between

Agreed. A large amount of time also goes into things like making figures, which is mostly time-consuming grunt work. I think the key is differentiating between creative work (which is better to be done deep with fewer hours) and grunt work which is almost purely time. Both are needed for a sucessful PhD - few are good at both and it is hard to switch between the two.