Question about practicing aiming with a different ADS sensitivity

A lot of pro players and people in general use a lower ADS and Scope sensitivity than the regular, hip fire sens. So my question is, how do you practice? Do you practice both or only ads? Cause if I'm used to flicking on a sensitivity 2x times lower than my hip fire sensitivity, my shotgun shots are gonna suck.

And what about muscle memory? If I practice aiming with my ads sens for 2 hours straight, my shotguns will suck and vise-versa. Thanks a lot guys!