Like others have mentioned before I got the Hassle-Free trimmer solely because it uses used blades. Works great, but I rarely use it. I just use the blades free-hand to trim the backing paper. Also use them ti open chop packages, UPS packages, the wrap maround length... etc.
Frankly anywhere I need to cut I use a used blade. Then I put them into a box marked ***Sharp*** and keep my hand out of it!
I have a parts bin drawer thingey near my mat cutter that I keep my new blades in. Another bin/drawer in the thingey holds my used blades. When a new blade goes in the used one goes right into the old drawer.
Keeps me from cutting myself, (and customers!) Then when I need one I know where to get it, and when domne using it I throw it right away. Hate having the used blades lying around just waiting to cu tme (or my customers!)