I marked 6-10, but it's actually 11 most of the time. 7 drivers (avengerSS, surge, orc, TL, and RR are staples), 1 mid (wolf), and 2 putt/appr (rhyno, pig). And then one that I use solely as a putter (POLECAT). Always different molds. I know i need to add a couple mids, but I usually use my putt/appr discs for those situations. I mostly play my local courses, which offer a good variety of play (elevation, low canopy, wide-open, windy, wooded, blind, short, long), and this collection seems to be a good general purpose set-up.
My reasoning is they all serve their own special purpose, and I really see no need for back-ups IN the bag. Those stay in the truck.