How often should you exfoliate ??

no they just want you to buy it again, i say 2 times a week would be the best option

with my very sensitive skin I exfoliate once every two weeks~

I use my chemical exfoliants 2-3 times a week :) (both BHA and AHA)

To be on the safe side, I always use twice weekly. But I notice some people use everyday since their skin can tolerate with the chemical exfoliant.

It depends on the product really. The two you attached, I would say 1-3x a week. Cleansers normally contain very low percentage of BHAs and can be used daily, leave on products with around 1% could be used roughly every other day, stronger ones a couple of times a week. And it depends on your skin and how much exfoliation is really needed. You can start on the careful side and increase the frequency gradually, letting your skin adjust.