Hi! My name is Maddie and I recently graduated esthetics school. You can over-exfoliate and it's almost even worse using an exfoliator during winter because it will dry out your skin and make it more oily. If you're going to exfoliate, do it once every two or three days/a week and use a very mild, gentle exfoliator. I use the neutrogena gentle exfoliator in cucumber and even though my skin is very oily, I noticed that it dries out my skin when I use it every night. Make sure you moisturize every night and in the morning if you need it. It's usually the best to exfoliate every week to slough off dead skin cells.