Trying to work on too many projects in one day can be bad. There's a line I always think about (I forget where I read it): "Context switching is expensive." Expensive in terms of energy burned trying to get back "in gear" after switching contexts. Comics work involves many levels of nested problems and projects and it gives the brain a good workout to keep track of all the levels of tasks and problems. So don't make it worse by switching out whole projects/contexts too often or you'll get mentally tired quickly, and begin to feel exhausted and cranky.