I've been using the Pomodoro Technique for a while and it has been helpful. Primarily I use it for trying to stay more focused and overcoming procrastination to get to the level of work I think I should be doing, not really to excel at this point. Being able to look over and see you have 10 min until the next break 1) allows you to work until the next break because there is end in site and 2) makes you work harder to try to complete a task in a work period.

It reminds me of a quote by Royce Gracie on the topic of time limits in mixed martial arts fights... "if I [was to] drop you in the middle of the ocean and you look around and there is only water, most of the people - 99 percent - would drown on the first night. If I drop you in the ocean and fly away but tell you I'm coming back the next day to pick you up, you don't have to go anywhere, just float around the entire day. I'll come back and pick you up and you'll be there waiting for me. That's what the fighters are doing now. They know there is a time limit"