I thought you were talking about steel cases and other outer parts. I still own two Rolex from the sixties and "keep alive" (my women’s watches) two very old ones and a Tudor. My 1967 Submariner got wet a couple of times but the movement, once fixed, still works perfectly. Let's see what the fate of my one year old Tudor Black Bay movement will be in fifty years. Well, actually I won't realistically witness it, but anyway.
Thanks a lot for the information.
Simone