Do u know how many watts per sq ft he is running? Getting 2-3 gpw at 45-50watt per sq ft is obviously big difference from 2-3 gpw at 20-25 watts per sq ft.
Here is an example... 2 x KingBrite 320 boards > [left = 288 LM301B 3K / 660 epistar red | center = 288 LM301H 6500K | right 288 LM301B 3K / 660 epistar red], board spacing > [left tent wall to board = 13" | center spacing between the (2) boards = 16" | left tent wall to board = 13"] and each 320 is running 250watts at the wall , that's 500 total watts / 25 square feet < (that's for are 5 x 5 tent) = 20 watts per square feet, and that tent when done will pull just over 32 zips from 6 different plants in 110 days from seed. And I have tried 25 watts, 30 watts, per square foot and there wasn't enough of a grams per watt increase for me to use 30 watts over 20 watts a square foot. Also if I veg my plants for 60 days instead of the 30 days that I normally veg for, I can pull over 55 zips using those same 2 x 320(s) @ 20 watts per square foot. And as a side note... I am not really using all that 5 x 5 area, its more like 4.5 x 4.5, so I am probably putting out more than 20 watts per square foot, but its still pretty amazing to use below 30 watts per square foot and pull that much bud constantly without much effort, (a single top at the 5th node, then I let them go)!
Day 28F, 30 day veg rotation!