Somewhat related to what your asking, but according to a rather famous study done by KA Ericsson on Deliberate Practice and it's effect of learning, the optimal

Somewhat related to what your asking, but according to a rather famous study done by KA Ericsson on Deliberate Practice and it's effect of learning, the optimal learning (for violinists and I've seen similar results when applied to my Mixed Martial Artists) is 90 minutes of deliberate activity, a short break, 90 minutes of further deliberate practice, followed by a second break, by another 90 minutes of deliberate practice. (Time for training sessions is of course the enemy, and practice is deliberate enough to cause mental and physical fatigue). Source: http://graphics8.nytimes.com/images/blogs/freakonomics/pdf/DeliberatePractice(PsychologicalReview).pdf http://graphics8.nytimes.com/images/blogs/freakonomics/pdf/D...