For me, sulfate-free shampoos are a must. After a bit of experimentation, I found that SLS and SLES actually aggravate my sensitive scalp and make dandruff even worse! When my former fave sulfate free line changed their formulation and it didn't agree with my hair, I had to do some more searching to find a new one, and tried the Body Shop and Lush dandruff shampoos which do contain sulfates - never again! They instantly made my scalp more sensitive, itchy and flaky. Luckily I found a new line (made by a local Australian company, Beauty and the Bees) which works wonderfully. I've never felt the need to wash twice with my sulfate free shampoos though! Thats a new one! (And I have reasonably thick hair). It does take a few weeks for your hair/scalp to normalise after switching from Sulfate to non sulfate products though, perhaps thats what you've experienced? I also don't use a conditioner with mine - just a few tablespoons of apple cider vinegar in a litre of water as the last rinse after the shower.