Dr. Krejci told us that if you shave daily, you'll probably know within a week, if your new razor is not working. If you shave less often or have skin conditions like razor bumps, you'll need to wait out the full trial period to assess how your face is responding. Most electric razors (including our top picks) have generous return policies for this reason: Philips Norelco offers a 45-day money back guarantee, while Braun offers a 60-day guarantee.