I've been looking at different books about personal training and weight lifting and the like recently, and i was looking things like the High intensity training style of weightlifting. Its a style of weightlifting discovered by Arthur Jones (The Nautilus Machine guy).
Basically, the premise is that you can get more effective results by using shorter, more focused, and intense training sessions than by spending hours at the gym.
Seeing as, basically, you're using muscles to play guitar (duh), wouldnt it then follow that it would be possible to practice in a similar manner to this, and get similar results? I know there's diminishing returns when you get people that are crazy and practice or play for 8 or so hours day. Would it stand to follow, that as long as you're covering all the major aspects of playing you normally would in a longer session, in an hour or so of practicing, and drill them till your hand hurts, you could be just as effective?
I have friends that spend hours in the gym. Every day. Every night. Two hours 5 times a week.
I can get my workouts done in about 45 minutes.
There is a theory on the waiting time between sets, that when you wait longer, you build up testosterone, whereas when you wait shorter, you build up growth hormone.
I typically do high reps high weights fast with short rest periods. That's just me.
When it comes to guitar, I do the same thing. I do highly technical fast paced drills in short amounts of time, and I don't think it's hindered me, but only made me a better player.