Larger pot size equals larger auto, and mine never got real big with two 400 watt lamps(MH and HPS). Hell I even went from 2 gallon to 3 gallon pots with no discernable increase in auto size. Grew Mephisto strains, happy with ganja, grew fast buds and was disappointed. Good luck a few autos did get over 2 feet though.
3 gals is plenty, 5 is overkill
Oops, over kill, lol. I was told 3gal or 5gal if you can do 5's do them. So they are in 5gal, ones in a 2gal, and of course she's the biggest!
Ok, so I think:
1 plant 5 gal
2 plants 3.5 gal
4 plants 2 gal
But to maximize yield which strain and how many plants you say me to put in my grow box??
Grow them out and see what does best for you. Thirteen years of growing/breeding autos, no more than 2 per largest container.
There have been numerous replies, so just grow and enjoy, learn from your mistakes.