S&W has never instructed or recommended removal of the cylinder for regular cleaning.
Same here, and for the same reasons. Especially with the NM 66 in both 4.25" and 2.75", no gas ring typically means a fair bit of carbon crud in the cylinder. I also put either masking or electrical tape around the screw before removing/re-inserting. Even with the correct size screwdriver, one slip = a scratch you have to live with for a while.I do clean the cylinder and yoke every cleaning. I don't own guns that I don't shoot, so it's turn in the rotation might be a while.
When I was in the police academy in 1986 we were issued model 10's and were instructed to remove the cylinder for proper cleaning. It has just stuck with me.
So do you think it is a bad idea to repeatedly remove and return that screw to its hole, over and over again over the lifetime of the revolver? Or will it likely not harm it? I'm thinking of stripping the threads on the frame (screw itself is only a few $'s on Brownells).