What a coincidence ... exactly what I have been saying including,

"And advantage players at any game need to be wary of fatigue. Regardless of whether you're a blackjack card counter, dice controller at craps or a video poker player who sticks to expert strategy at the best games, if you play when weary you're going to start making mistakes. Get some rest, and come back to the games refreshed."

This is the main reason APers don't play on and on. We all have our own personal limits. And, at least in my case, I have lots of other activities that I enjoy. More than once a week gets old fast.