Damage from lightening is a function of how many shades you lift and how many times you repeat the process, bleach baths are not less damaging them a well done single step lightening, the only benefit is that you are going slower so reduce the chance of overprocessing a section (or the whole head). Sulphate shampoos in themselves are damaging to hair and skin, there isn't a cat in hell's chance I'd leave that soaking on my head repeatedly.
An Indepth Look at Porosity | Curly Nikki | Natural Hair Styles and Natural Hair Care
2a-2c, medium texture, porous/ colour treated. Three years CG, growing out mechanical and chemical damage = breakage and very high porosity. Past armpit length heading for waist.
Treatments: Komaza protein, Komaza Matani, coconut oil with sugar syrup. Hairveda Sitrinillah
Leave in: Fructis Sleek & Shine (old), Gliss ultimate volume
Styler: Umberto Giannini jelly, Boots curl creme, Rockin RInglets
Experimenting with: Mega-Tek, Curl Harmony reviver, Elvive Full Restore 5.