But isn't the extent of the wound correlated to the amount of growth factors? If I scratch my skin, growth factors will occur. If I cut the skin, more growth factors will occur since the damage to the skin is greater. If I cut the skin deep enough, scarring occurs. So if you wound deep enough but not too deep, wouldn't you maximize the level of growth factors? I'm not sure because I have no biology training. But I can't help but wonder if microneedling at 1.5 mm yields limited results because it's not deep enough to trigger the best response.
Sure, but below a certain depth and you will get scar tissue (fibrosis) and not normal skin, hair does not grow in scar tissue.