@MaxMMA
I agree with the second part, but not with the first.
-Instep, toes or ankle against an elbow, is very bad news (and if you put in the mix a shin/knee check for mid kick, its even worst)
-From my experience, in TKD, the bag work done is not enough to condition the feet. It's not the most used training method.
-Hell, you even see kick-boxers with "weak" shins from low quantity/quality conditioning.
-TKD uses foot guard. ITF big ones, since the hands are more often up to protect the chin from punches, so you tag the elbow a lot more often than WTF with both their hands down. But even they use instep protectors...
So for me, it's TKD instep kick to the head, MT shin kick to the body,leg... Some times I might try a risky kick with the ball of the foot to the liver, but only if i see a big, slow opening.
I don't have a clue about instep conditioning in karate though...