It's been my experience that for inside grows, that have a faster 'turn-around': two ounces per two gal pot is a good yield, depending on the strain. Big Bud and a few other high yield plants will manage 2 oz easily.

Outside is another matter all together. I have mexiseed sativa's that routinely yield 2+ lbs per plant. This is after I have 'sexed' them indoors, transplant outside at about 5 weeks, and allow them to revert to vegging.

The problem will be consuming a bunch of time waiting for that one 'girl' to show herself. I say, plant four to six, and if you only want one, just cull the rest. One other issue you might want to consider; some bag seeds can produce a very high rate of hermies. Check closely for them...B