Ya know it's hard to say with practice cus I'm still trying to find out how to do it best. I'm still not practicing, but with my friend, it seems like just working on 1 or 2 things for about 60-90 minutes works the best. He's not the most natural player so he really has to do things over and over again if he doesn't get the move from the beginning. For example, on Thursday I showed him this move: http://www.youtube.com/watch?v=Y580jXnbp4I
and it wasn't coming naturally to him at first.... Quite a few times he went behind his back instead cus that's what felt natural. It took him about 20 minutes to get it where I felt like it would actually work... then for the next 20 he just kept practicing that move and pulling up for a jumper... then I had him do that move, go under his legs again, go right, and then finish with a layup... then the move and cross over left and finish with either pull up jumper or a lefty layup. That took up about 65 minutes, and then for the next 15 minutes he just did the move and then did whatever he wanted to ... so either pull up, cross over, cross over to spin... anything.
So yea that took about 80 minutes... and the whole time he was doing one move and then counter moves based off that move... and to me it was necessary and a great practice session. Now he has a new move that he can continue to practice and then use in games.
So yea I honestly think that just getting in some warm up shooting and ball handling, and then picking 1 or 2 moves that you really want to hit hard might be the best way to do it. Once you feel completely comfortable with the move, then you can take it to 1 on 1 with a buddy, and then a game.