I always ride with body armour but just knees and maybe elbows (plus an EVOC back protector pack since I broke my back)
I echo that skills courses are the best but there is an element of confidence it gives me when doing more technical trails. The elbows come out for steep trails. I’ve also got a TLD vest I use for uplift days too – but I think this will stop sharp rocks and abrasions rather than bone breaking impacts.
Collar bones are a tough one to avoid due to how they usually happen.