I feel like every hour was worthwhile, whether it meant getting one more standard under my belt, getting a tiny bit faster at a lick, memorizing something a little better. I take all these things with me unless I never practice them again. The best things to come out of this sort of exercise are little epiphanies, like the technique I discovered for memorizing intervals. Those happen more frequently when I'm taking something further than usual, practicing a song to death, playing a single note for an hour, crazy things like that.

My normal 10-hour day now pales in comparison to this. There's something to be said for that feeling. Things seem easier when you know you've done something much more difficult before.