To give an example of how a certain space works for me at exactly 50 wpsf (3-600w hps hortilux super hps , 3-600w sunmaster mh conversion, total initial lumens 421,000 mixed spectrum , homemade bat-wing style reflectors with sun spreaders, magnetic ballasts,7 foot high ceiling ,low pressure aero, no media, 33 plants, vegged for 1 month, a pheno of Reserva Headband that produced the best out of 72 seeds, modified version of Fatmans DIY hydro nutes, 40 gallon reservoir, 90 green 360 sprayers , temps always in the ideal- .73-.78 gpw.
If I went all hps the yield would probably go much higher ( around 1 gpw) but with side by side identical room/strain research I concluded the quality was superior with 50/50 (as opposed to all hps) hps/mh in terms of nugget density. Just an example and a few details to give you a better understanding of the chain of variables that can affect yield.