My usual "go for a shoot" setup is one body and three lenses (typically 21, 40 and 90 with APS-C, 35, 50, 90 or 135 with "full frame"). I don't change lenses all that often, though, as I usually try to 'think in the field of view' and look for opportunities that whatever lens I have on the camera is able to capture.
I probably miss a bazillion opportunities a day because of this, but that doesn't mean there aren't 10,000 that I can exploit ... I only have time to do a couple of dozen to a couple of hundred of those anyway. ;-)