I have actually been thinking of carrying my 1911 instead of my Shield. But I want more time in and out of the holster before I do that. I'll admit, I am a little concerned about carrying cocked and locked. I just need more practice to make sure I never inadvertently flip the safety off somehow while it's holstered.
That is the only thing preventing me from making the switch now. Oh, and a holster!
I carry in a Serpa. Many people are not on board with that holster.
Muscle memory. Pure and simple. Put it in the holster cocked/locked and leave it alone. If your safety is not properly fit and loose then get that looked at. It should take the proper effort from your thumb to disengage.
You know some people that will take care of this if need be.