I've never had to cut Nestle's nails because they get worn down from running in the back yard (there's a small patch of grass, a concrete patio, and a large section of grass). Running in the yard doesn't seem to do the trick for Hobart though so I have to cut his pretty regularly. I wait until he's sleeping and just do a couple at a time because that's all he holds still for

I use a clipper that has a safety guard so you can only cut a certain amount of the nail. This has been a great feature for me because all of Hobie's nails are black except for one and I've never cut the quick once!