you know, i think you might have a point, Julie, about horses that are frequently worked hard? see, i never noticed this until this thread came up, but i haven't spied any salt/mineral licks in the barn where my leased horse is boarded. there are about 15 or so horses, and while i haven't gone into each individual stall to check, i know Raven doesn't appear to have one, and i haven't noticed any others. we allllways had salt licks (just white, no mineral) in our horse's stalls when i was a kid; they never overused them, but also weren't worked a heck of a lot.
the vast majority of horses in my current barn are ridden quite frequently, and Raven is worked 5 days/week. maybe this has something to do with it? or maybe they have licks out in the field that i haven't seen or something; not sure. hmm...