I've always worn a helmet. Where I started out taking lessons, and I was only there seven or eight months, you HAD to wear one if you were taking lessons. It sort of became ingrained then for lessons after that.
When I got my horse... oh, Lord. Even now, I wouldn't dare work my horse without wearing one. I've been tossed off too much and into walls and such, so with mine, I wouldn't ride without one unless I was just walking him around.
On other horses... On my trainer's horses, I won't wear a helmet, even if I should. They're really well behaved and I've never seen one of them act up that badly, and they've never doen anything with me on their back in all the times I've ridden them. So, I don't wear a helmet with them.
It just depends, I guess.
"Yes. Like 'Wendy'...With a T."