i've thought about this many a times,
when i press the clutch, my foot is in the air at all times. there is no heel contact what so ever. basically i'm not clutching with my ankle, i'm clutching with my whole leg. i've kind of tried with the heel but it just didn't catch right or something, i think the play on my clutch pedal is too long or i've just learnt that always press the pedal to the end when shifting and stuck with it.