I think you may have picked up on this from the 'Bush pilots' thread and the apparent lack of checklist use and that is the typical situation where check are memory, muscle memory, indeed. Skydive flying is another example. You won't last long as a skydive pilot if you insist on having a checklist as long as your arm.
From my own experience in certain scenarios a checklist is merely a hindrance.
Redsnail put it best in the other thread:
Well, my old Chief pilot said "if you know why you're doing the checks, then you don't forget them".
They're mainly flying fixed gear, single engine constant speed prop a/c. It really isn't rocket science.
She's been there and done that so she knows what she's talking about but you have to remember these guys are extremely current in the aircraft they fly and it's SOP with the operator.
That doesn't mean you should toss your checklist in the back and try to guess your way through the checks.
Instructors may throw their hands in the air as such heresy but remember most have never worked in that kind of flying and even if they have they're going to teach you properly.
So stick with your checklist for now. Maybe one day flying your little Cub or whatever you won't need it anymore.