To answer your question - Yes. To explain my answer - Sometimes I use a trow away piece. Sometimes I don't. (Like the old commercial "Sometimes you feel like a nut, Sometimes you don't.") Depends on what blade I use, what wood I use, and mostly if I remember to add one. When I am cutting, I use my 4 in 1 tool. Cut awhile and while giving the saw a break, sand the bottom of the bottom piece with the 4 in 1. Gives some support when sanding. Cut some more, sand, etc. When cutting is finished only a little left to sand on the bottom. Plus I think removing the fuzies as I cut makes the wood move better. I hand sand or use orbital sander. Even when I have piece wraped in painters tape, I will sand but by hand then.
Larry