"Distance" setting in winbox/advanced

What is best practise?
Leave it ´dynamic´ or set a distance?
If distance to be set, pick distance fm AP to furthest CPE? Or maybe 1 km extra to make sure?

Would fixed setting give better performance than ´dynamic´?

Reason for thinking fixed might be better (if proper value choosen) is the cpu doesn’t have to decide and adjust every cycle?