I always see reviews talking about the dents made by an office chair on mats but I never experienced it myself. I bought an amazing tough mat a while back but needed to upgrade to a larger one. I received this at my doorstep and in no way was it flat. Which I wouldn't care about except for the fact that it is supposed to be flat because if it is this malleable then a chair would certainly dent it right? Yup. I'm only about 140pounds plus the chair of course and within 5 minutes of sitting in the chair on the mat there were definitely dents I could hardly "scooch" out of. Worse than a carpet.
While it serves the purpose the desk chair used on the mat makes grooves in the mat which means after continuous use it will be needed to be replaced after a small period of time.