How fast does bacteria or germs spread in the body when you touch with your feets or hands on something?

I know it's not good to keep washing the back of your hand since it might damage your skin faster (correct me if I'm wrong please) so I usually see people washing more only the palm, is it both because bacteria and germs didn't get to the back or is irrelevant the ones that do or just for not damaging the skin too fast? The palm of the hand doesn't seem to get damaged or appear damaged so fast like the back of your hand if you wash it off a lot.