Prozac is a great solution to a depressed clutch... :tongue:
Anyway,
When the clutch pedal is depressed, the clutch is "disengaged", meaning it's not touching anything, meaning no wear is possible, nor damage (for purposes of this discussion, anyway...)
Damage/wear occurs when the pedal is released or the clutch is "engaged"
Clutch damage/wear/slippage is exacerbated when, at the time of clutch "engagement", the engine and tranny are moving at different speeds. Bigger the difference, the more wear/damage.
When you blip the throttle, it raises the engine speed to match more closely what the tranny speed will be when you change to the gear you want to be in.
Heel/toe shifting is necessary b/c when slowing down to take a corner, you have to brake and downshift and at the same time since when you come out of the corner, you need to be in a lower gear for max power. If you don't rev match, the drivetrain will limit your power in that moment you downshift.
Solution: blip the throttle and brake at the same time, IOW rev-match AND brake.
And of couse, when the clutch pedal is in, or the clutch is "disengaged", do whatever you want with the gas--if the clutch isn't engaged, no stress is put on the clutch (in the traditional way).
NOT rev-matching contributes to clutch wear and tear. If every driver in every car rev-matched on every shift, clutches would last longer.