4 x 4 x 4 in a vert would be good coverage for one 400W bulb
For sure, it can work, it just depends on your setup. You can overcome other deficiencies with more light and get better results, but it doesn't mean it's worth the added costs. My setups maximize the efficiency of everything so that I can use less light for the same results as most other people. Increasing the light will increase my yields I'm sure, but is it worth the added cost and heat, etc.? I wasn't arguing the fact that it could increase the yield, I was argueing the fact that 50 watts/sqft is something you "have" to run to get a good yield. I beat most people's numbers with 30 watts/sqft while they run 50+ watts/sqft.