I've been pondering some situations lately, stemming from spots wherein you're theoretically happy to get your money in with an unmade hand. On that vein, let's discuss a few concepts:

1) If you're on a draw with at least 45% to win the hand, you're happy to get your money in on the flop. The theory here is that you're going to win a fair portion of the time, so winning big pots is good. Plus by betting aggressively you get some of the hands that will beat you 55% of the time (single pair hands, for instance) to fold, increasing your equity. The counter argument is that you'll know by the turn whether you're going to hit half of those outs, meaning that if you play it smaller, you stand to lose less the 77% of the time you aren't winning by the turn. The question here becomes how to balance winning more when you win (and got the money in) with losing less when you lose (and didn't get the money in). Plus the fact that trying to get money in after hitting the turn becomes more difficult...

2) If your opponent is on a draw with at least 45% to win the hand, you're happy to get your money in on the flop, as you're still going to be at least 45% with your made hand. The theory here is much the same as above. The counterargument is exactly the opposite, however. If we wait to get money in on the turn, then we can provide a reduced variance play. Since on the flop we're only 45-55% to win, but on the turn we're 66-80% to win, we're much further ahead on the turn. Plus, we're 100% to win if our opponent folds, and we win a bigger pot if this happens on the turn (assuming some money went in on the flop). The quest here becomes how to balance getting your money in when slightly ahead versus when way ahead, and how factor in paying off draws vs folding incorrectly.