In reply to johnlc:
Great discussion point
My two most regular climbing partners, both of whom are solid E5 leaders only carry wires up to size 9. One carries a double set of DMM Wallnuts and the other often carries the best part of four! sets, comprising both Wallnuts and DMM alloy offsets.
However, I routinely carry DMM Wallnut sizes 10 and 11, plus an old WC Rockcentric 6 on wire which would be the equivalent to a DMM Wallnut 12.5 if they made such a thing. I rack the Rockcentric on the same krab as my large wires. (FWIW I really don't like the shape of the larger WC Rocks.)
Another climbing partner and well-known contributor on here takes a similar approach. In addition to DMM Wallnuts up to size 11, he routinely carries two medium BD Hexes on wire but racked separately.
None of us use WC Rocks. None of us carry hexes on tape/cord in Summer even on easier routes.
So, loads of options, all of which seem to work for different people. You just need to experiment and find out what works best for you...
Have fun and climb safe.