Yes. Helmet. Always.
Honestly there isn’t a whole lot more for me to say on this topic. I wear my helmet every single time. No helmet? I don’t ride.
Endurance is pretty far behind the times when it comes to rider safety. Most rides in the SE and the ones I did in the Midwest only require a helmet for juniors (under 16 at start of ride season) and “recommend them” for all others. I’ve been to rides where people don’t wear a helmet and I have no clue what they are thinking. If I was a ride manager I’d require it. In fact, I recall an entire Facebook thread on the endurance group a couple years back where people were complaining that managers were starting to require a helmet for all riders. It shocked me the excuses people came up with.
Personally I’d love to see endurance make safety vests a requirement as well. The risk level is nowhere near that of eventing or really even of stadium jumping, but there is a level of risk higher than the other arena based disciplines and I believe the safety requirements are pretty non existent currently. Endurance is still rooted in the days of minimal governing body involvement and a strong “don’t tell me what to do” attitude which is fine except when safety is concerned. I mean this is the sport that recently put k tape on the banned substance list. For a sport that is dedicated to horse welfare a little bit of rider welfare wouldn’t be amiss.
But I suppose that is a bit off topic.
Helmet. Yes. Always.