in general you're not encourage to exfoliate everyday. it still depends on the product concentration u use, the type of acid u use and your skin type. BHA more than 0.5% shouldnt be used everyday. AHA of more than 4% cant be used everyday too (if not mistaken,im not so sure about AHA). PHA is generally very gentle and can be used everyday. while for LHA, it depends on the concentration as well but generally its quite gentle so if your skin is able to handle then its okay. its important to let your skin restore itself and rest as well