Can I slab roll clay a few times, folding it over and re-rolling it, as a substitute for wedging?

Question

I just have a hard time wedging, especially when starting with mixed pieces that came from other projects.

Answer 1

Not as effective, but would work.
Make sure you do it a lot of time and do not work in air.
You might try to first work the older pieces, with some new clay if needed, till they are supple enough before you start wedging the whole lot, that way you are sure the old clay is going to be worked in right, and not lumping in the center.

Answer 2

folding and refolding will likely work more air into it rather than taking it out, wedging is to remove air pockets.