What I'm curious about is, if you can only be max productive at X for maybe 25-35 hours a week, can you also be max productive at Y and Z for 25 hours each in t

What I'm curious about is, if you can only be max productive at X for maybe 25-35 hours a week, can you also be max productive at Y and Z for 25 hours each in the same week, and how different do Y and Z have to be from X and from each other for cognitive fatigue not to carry over from one to the others? Cos if you can be max productive at 3 challenging but sufficiently different cognitive/creative tasks for 15-25 hours per week each, that sounds like a super fun, productive, efficient, sustainable, healthy, and balanced life