I think 19 hands is an EXCELLENT way for beginners to learn to play. It makes you only play good cards, so that when you do hit something on the flop you have a good chance of winning the pot. Beginners are for the most part entirely too loose, and will play anything because it's fun to be involved in pots. So if you use 19 hands, you will be getting into pots with good cards, and not getting outkicked because you decided to play Ax and hit an A on the flop, only to get outkicked .

As far as when it is time to move on, if you play for a long time using 19 hands, you will begin to see how people play and will get better at putting people on hands, stealing pots, etc., and then you can loosen up some and play your own game.