I imagine that any feasible scientific experiment would measure only a crude approximation to reality. How can you randomize someone to a job and a way of working? Most people are not capable of concentrating for four hours a day, or have jobs that don't permit it.

At best you might recruit some undergraduates -- nearly all psychology subjects are college students -- and have them do some artificial task one way or another for a couple weeks. I find anecdotes from successful musicians, scientists, and authors more persuasive than data from an contrived scientific study.