Helmet hair. Once my hair gets compressed by a helmet, nothing other than a shower can fix it, and we don't have showers at work [not an issue as I'm remote now].

I live less than a mile from my former cubicle, and my old commute was mostly through a park with two road crossings. There was no reason to wear a helmet.

If I'm on a longer road ride, or riding off-road, I religiously wear a helmet. If I'm riding lift-assisted downhill, I wear a full-face helmet.