I would say I use heat once maybe twice a month but that is probably more out of not wanting to do my hair than the health of it-just never liked having to blow dry, flat iron, then curl (my hair won't hold much of a curl anyway). I did do it a lot growing up tho.
I do relax although it gets farther and farther between, contemplating letting it grow out again but I hate the in between stages. I did braids recently as a protective/low maintenance style and loved them but hated the shedding I had when I took them down. Plus my hair texture doesn't hold the braid so I can't wear them long (even when not relaxed it wont)
My biggest problem is that I don't get it trimmed as much as I should so my ends are a mess. I think this is old fear from growing up when I would go for a trim and come up with a damn cut.
Currently my length is about to bra strap. I usually air dry and wrap at night.
Good luck to those that do the challenge w/ Kha and I would still enjoy any tips shared