Holy shit we agree on something again! I won't believe anything over 2lb from a true 4x4 best I've done is 1.8 same situation wall to wall buds at least 5 foot tall plants I don't use co2 so maybe that could help get over 2lb.
a pic is worth a thousand words
everyones talking about 4x4 space
watts per sq ft,
type of lighting,
cO2,
proper enviroment
proper nutrition
pest free
why not 3 units per 4x4 provided you got enough light, lots of guys are bumping yields with strategic supplemental or lower lighting
id refer to watts per sq ft vs grams per sq ft
and remember that LED should produce a min of 25% more up to 33% using equal watts compared to HPS
having said all that id say its impractical to think your going to get these yields every harvest and with every strain.
setting the average goal at 2lbs yield per run in a 4x4 tray using 1000 watt hps seems reasonable