drills
Because of the layering of myelin in the insullation of neural pathways, which helps to establish the proper firing sequence for our muscle memory; you can loose efficiency if you don't revisit a programmed aspect of performance on a regular basis. The neural pathways experience a slight degradation over time if not regularly coated.
If you are 100% with a specific drill, then I would briefly revisit that drill perhaps once or twice a week to keep the pathways coated and firing properly.
Wait more than a month and you may lose a little ground.
If you don't know about myelin, you might wish to read the "Talent Code" to learn about its effects.