The one rule that I've always found to be not very practical is the lost ball rule.
As an example, let's just say that I hit my tee shot and feel like I know where it went. When I get there, for some reason, I just cannot find it. And because I thought I knew where it was, I didn't play a provisional ball. The course is busy and there may even be someone waiting to tee off. What do you do? It's just not practical to turn around and go back to the tee.
I've always been a stickler for the rules. Most people that I've played with, just take a drop near where they think they lost the ball and take a one penalty stroke. This is of course not playing by the rules and that's why I take with a grain of salt the scores of the people I talk to about golf.
So what do you do?