You're just developing the muscles in your hands, so IMO you've got to go about it as a weight lifter would. That means letting your hand recouperate after a hefty practice and whatnot (ie a day or per usual workout schedule). For most beginners this comes naturally because, as you said, you quit when you feel you're not making progress and so it gradually progresses into some decent muscle recognition and strenth. If you want to go around this natural learning curve buy a book or take lessons then go at it as a weight lifter does but remember everything takes time. The more time spent with the guitar the better of course - you can only benifit from playing the guitar.

... Unless you're playing to frequently with terrible technique and no stretching.