I have had what I would call mildly heat trained hair. I just wanted to say, neither of these disappeared for me when I was frequently blow drying/flat ironing. As stated earlier wash n gos cause breakage for lots of naturals with all different types of textures.
I ended up going back to natural styling and had a harder time enjoying my own hair because I knew there was damage. I lost even more hair because I'd weakened my strands with heat and I hadn't yet made the "wash n go = breakage" connection yet.
I do agree that most people cant see heat damage if its not alot of it or its all uniform. Most people outside of the hair world just see long hair with alot of texture. Other people thought my hair was really nice. But guess who ultimately hated it? Me. I didn't have loads of breakage from SSKs, but even some was enough for me. And, I couldn't stand knowing they were there even though no one around me could tell. Just the same I couldn't stand having heat damage even though I knew the people around me didn't see it,
I knew was there.
To rid myself of SSKs, first I had to trim off the hair I had fried with my flat iron and knotted up with my wash n gos. Then after researching I learned that wash n gos are not everyones friend. Keeping my ends smooth became a priority. When I shingle or twist my hair I finger curl the ends of each section so the ends stay aligned and going in the same direction. If I do a braid out I put a rod at the end. I havent seen a SSK since!
Also, keep in mind that everyone's hair doesnt respond the same to heat training either.
On the flipside, some of us have retained healthy long hair because they use heat.