Do certain bits need a bit guard? I've never used them before, but I just bought a Dutton O-ring smooth mouth snaffle bit, and I'm not sure if I need bit guards.
I watch the sides of their lips for pinching, including if I get head tossing while riding. My open horse I use the thicker neoprene ones because he has a finer muzzle and mouth and they make the bit fit better.