The dorsal side of my shaft was more resistant. I’m guessing the skin is tougher there from clothing abrasion.
I generally wore tighty whities the days after a burn. They reduced friction by holding everything in place. I wore boxers at night, either underwear alone or with loose sweatpants, to allow plenty of room for erections.
Wearing a condom all day would likely give me a thrombosed vein, but I’m extremely (as in unusually) prone to them. Might be ok for most. I don’t think it’s a good idea for anyone who has had a clotted vein.