I don’t do much trail riding but did free lease one of my Arabian mares to a woman I know who did. As she was nearby, I agreed as I was doing nothing with the mare who was youngish (8) and completely sound barefoot. I was welcome to visit any time.
On the second ride the mare whacked herself mid left front cannon on a sharp rock (boulder) in a tight part of the trail. The gash wasn’t too large - about 1" wide- but deep. The leasee didn’t think much of it and didn’t treat other than cold hosing one time. In a few weeks the would healed over with proud flesh. When I saw this I called my vet who cut off the PF and gave me a tube of Panalog. I handed the leasee the vet bill and cancelled the lease at the end of the month because she refused to use leg protection on my mare which I requested after the injury.
She came back a couple of months later begging for the mare back because she could find a better horse to lease for free and promised to use thick flannel wraps (not polos). Had to think about it but eventually agreed. The wraps she bought were easy to put on and take off with 3 or 4 velcro strips. IMO, unless the trails are wide and cleared of brush and large rocks/boulders, some sort of leg protection should be used.
As far as bell boots go, any good farrier will tell you they protect the heel bulbs from a strike but will not prevent a shoe grab. They don’t cover the bottom back of the shoe.