This has happened to me many times on the range:

I get a big ol' bucket, & start hitting great. I'm hitting everything long & straight. People around me are noticing...(actually, that's probably just my imagination LOL)

Then, after about an hour, I start shanking every shot & no matter what I do (move away from the ball, keep head still, etc..) I still shank it! I figured that my swing just broke down due to fatigue & my session was over.. PERIOD. But I wonder... I'll bet good players don't have that happen on the range - or if they do- they can fix it.

What do you guys think? Is it fatigue or is it just a bad swing finally revealing its errors?