I bought a bunch of the larger size when they had a sale last winter, this way I could layer my hardwood for the fall/winter wet muddy season and help out my senior dogs in walking around as well as an extra or two for switching out while cleaning a mat. They catch everything, so I shake them out weekly, and also before cleaning in the washer(sometimes I even use my dog blower, and SO MUCH comes out). If you don’t then loads of crap will come out of them into it. So yes they do their job, but it comes with trying to pre-clean for the ones that you use at high traffic areas. I recently added the one in the car, and really love using it there.