That argument is correct, to a point (but it more often abused for the theory of it by people who've never grown before*) - the issue is balancing out the light's distance with its coverage.Right i hear ya,but what im sayn is that having the light closer = denser buds and higher yield. Now the argument goes that if you have a 1000 that produces 150000 lumens and that light is 2.5 feet from the tops you losing some lumens. And if a 600 produces around 90000 lumens,but is a foot or more closer. you would be just as if not more efficient. Like i said ive never grown with 1000's , but the argument seems reasonable.
Personally, I like having my 1000s mounted up nice and high and getting even coverage across a larger footprint.
You ever see a picture of a commercial op? Do those lights look to be 1' away to you, or more like 2-3 feet above the plant height?
They're higher, because if your light is that close to your plant, the effective footprint is minimized - the only plant that will get good light is directly under it, leaving all the others to suffer, even if they're within the 3x3 footprint recommended.
* Not saying it's being misused by you or that you've never grown before, just that a lot of people spout that argument without knowing that they're talking about.