I agree with many ladies, I think it's based on hair health, what kind of protectants you use and how often you do it, now with me, my hair hates blowdryers, but I'm trying to give it up, and it's so hard, but I hair likes curling irons, the flat iron is ok, but I don't think my hair likes the flat iron I have now, so I'm trying to go into another direction, right now, I'm not using any heat, cuz I'm too lazy.......but when I was in high school I use to curl my hair everyday also, I was not paying much attention, but I knew my hair didn't grow like it's growing now, and I have limited my heat use, cuz I know I can be out of control with heat, I'm a big heat lover, and I have to change that, so since I want length, I know I have to stop using heat as much until I get my balance correct....so it also depends on the person too....