I think I wore a helmet every now and again at the park when I was skating with a dude who was full on team helmet. He had just had a 5 day stay at the hospital and always wore a helmet after that. However, since he was a pretty gnarly transition skater the helmet didn't seem out of place.
I think I would have died in middle-school if the park my mom took me to didn't force helmets. I don't know what the fuck was wrong with me but not even able to really ollie, I tried dropping in (did not go well) and tried doing a boardslide on a super waxed parking block. I went straight to the back of my head on that board slide. Helmet saved me for sure. I still think about that fall today.