Finally science and information to back up my preference of work intervals ...

This article talks about effectively working in 90-minute increments.

Tony argues that we “should try to get things done in bursts of intensely focused activity, interspersed with periods of rest and recovery.”

I do my best work this way -- for example, my plan for today --- up 5:00 a.m., work on a script for 90 minutes, take a bike ride, back for e-mail correspondence, take a break to go to recycling, then back at the computer or to a meeting depending on correspondence.

Does this work for you?

Dave