The only short comins of tournaments when it comes to improving your game is that you can't determine who you'll play, which means that you could go through the field without a tough match so you don't get pressure tested. You could also go two and out to superior players that you couldn't beat even in a tournament or gambling, so you didn't gain any real feed back on your game, or very little in either circumstance.
Gambling has one advantage, you pick who you play and how you play them and you always have the option to play as long as you want to.
