If you use a candle to warm your hands, there’s a certain distance that’s optimal.
Hands that are too far away, and you don’t get any benefit from the heat of the candle.
Hands too close, and obviously it’s dangerous and will burn you.
But at just the right distance, you’ll get the most benefit from the warm flame.
CrossFit can be used to optimize your fitness, there’s a certain frequency that’s optimal.
Only come a few times a month, and you don’t get any benefit from CrossFit.
Come too often, and it’s obviously dangerous and you’ll get injured.
But find that sweet spot of work and rest, and you’ll get the most benefit from the effects of CrossFit.