You always see semi-auto capacities advertised as the size of the magazine +1 and I just wonder how many people regularly use that +1. I don't, but I am looking at getting a lower capacity carry gun and in that case I think I will.
If, by "+1" you mean a cartridge in the chamber, yes--a crunchenticker without a round in the pipe is about as useful as a rock if you're in a hurry. I normally down-load the mags by two rounds, though, so I should probably have answered no...