Uhhh...it doesn't depend on ANYTHING, the answer to how often to use 30% glycolic acid is NEVER. It is wayyy too strong to use safely at home. Mutti, heed my warning. It is too strong. My skin looks like crap if I go with anything stronger than 5% with my aesthetician. At 30% you'll regret it!
I honestly wouldn't recommend any sort of glycolic peel at home. These sort of treatments are really best done by an expert who can examine your skin properly first. Glycolic peels can cause extreme sensitivity (even when you have never been sensitive before) so you may end up with more problems than what you started with.
The best thing you can do is to use a gentle exfoliator 2-3 times a week after cleansing and before toning to keep your skin fresh and smooth.
I can only tell you what I have done, which seems to works for me. I use Skinceuticals gel peel gl at home.
I first went to a spa and had the peel done professionally a few times, I asked questions as she went along. I than found a reliable place to purchase the peel from, I have done two peels at home with much success.
I know people here feel that it really should be done by a professional and it probably should be done by a professional. But I am very careful.
I plan on going back to the spa sometime in Dec. to a professional to see how my skin is doing and to refresh myself on doing the peel properly myself.
I am by no mean recommending for anyone to do the peel themseves, I am just stating my experience.
Have you tried Alpha H Liquid Gold? It is a light glycolic which you apply every other night or alternatively use it on three consecutive nights a week. You can buy it on QVC UK. It has transformed my skin. I had a terribly spotty chin and nothing worked.I have been using this for 2 months and have had one spot which was tiny and went in 2 days. It is incredible.