Several players experience "playing in the zone, playing fresh, or playing to their fullest ability."
The biggest kept secret professional pool players don't talk about is playing when you are fatigued, playing when you are tired or judging shots after long matches.
It is common to see in tournament matches pros miss easy shots and think they miss because they aren't that great, "choked" or just couldn't get the job done. What isn't seen is how long their tournament day has been or how much time they haven't spent resting.
Some players can just run racks and in their final matches they look as sloppy as rookies on simple shots. The fatigue could be from "machine line production repetition," the concept that repetitive work can drive people to insanity. Or it could be from lack of rest.
Whatever the case playing fatigued is a serious problem for pros and amateurs alike. Some simple tips to keep in mind when playing tired are the same as when deciding to drink and then deciding to drive. Consider that being tired changes the way you play and the shots you can make.