There was a response on GolfWrx from someone about why rounds fall apart at the end and I thought it was excellent. Here is the link and the passage.
It’s not always clear what causes us to “tire” before the end of a round, so that takes a little investigation. We did an informal study 15 years ago by reviewing score cards from a half dozen clubs and found that holes 15 – 18 were the worst scored holes typically across the board of player competency. The reasons for that appear to be many -grinding on the game, thinking too much, fiddling with the swing, poor eating habits, too much beer, frustration, pressure, anxiety. All of those exact involuntary action from our systems.
So perhaps if you figure out a way to pace yourself and minimize some of the above, the tiring will be minimized. What I’ve found is that because all that is on the side of “hard to see,” it gets little attention. It’s not just in golf – that’s life. Find a little book by Hans Selye, MD and it’s all well said in there (“Stress Without Distress”).