with autos it's a guess. some are larger than others. it's easier to shape symmetrical plants than oblong plants, too, which with 2 you have to get them stretched out much further in one direction and that is more difficult to do with with least amount of wasted growth.
you can alays prune them to fit the tent - better than overgrown and mashed up against each other and the tent walls. If maximum yield is of utmost importance, this is the way to go. Do 4 and be willing to prune some back. can keep the strongest gowth and remove the less robust stuff. this is not the most efficient per seed, but relative to electricity and space it is maximizing your resources.
