the more stable your enviromental conditions are the higher your yeild will be, also the amount of weight you get per plant will also depend on how much room it has to flower, my first grow room was a 2x3x8 closet with a 400watt mh/hps switchable with a very unstable enviroment and i yeilded on average 8oz's off 2 plants, however i found that growing just 1 plant in the same amount of space yeilded 10-12 oz's, now i'm getting closer to 2 pounds with just 4 plants in a 4x4x7 space but my conditions are heavely monitored and adjusted accordingly and my enviroment is extremely stable, i cannot stress enough how much plants love a stable enviroment, thats what will get you your maximum yeild, consistancy