I buy yardage because you are paying for them to cut and they are not always as accurate with their cutting. I have a June Taylor Shape Cut Pro cutter (bought on sale at JAF) and it has grooves only at 2.5" increments so you could easily cut 10" layer cakes. It will cut 8 squares at a time.
http://www.joann.com/june-tailor-sha...n/2004133.html