I have always used the normal complement, put one in the chamber, and left it cocked and locked (safety on), without adding another round. I typically have 3 spare mags at hand; all are Wilson 8 round mags, for a total of 32 rounds. I also rotate with four more mags every 2 months.... probably unnecessary in this day and age, but old habits die hard. Why quibble over one more round ?
Then why carry 3 spare mags? Or two? Or one? Or any?......... I mean, I guess just the one in the chamber should be all you really need, right? Why carry the extra weight?