Kia,
Tracy and I were just talking about acv rinses the other day. I was telling her that I had slacked off of doing acv rinses (no particular reason, maybe just a tad bit busy and a teeny bit lazy). Anyways, I have started back doing them again. I was doing an acv rinse with each shampoo (usually shampoo every three days, sometimes less often, sometimes more often). I have never experienced any negative effects from doing them this often. I'll tell you one thing. When I slacked down, my scalp knew the difference. So, I vow not to slack off again, because I don't want my scalp 'acting up' (aka product build-up and oily scalp). HTH.