Is it overkill? Remember they are vertical watts so they cover much more vertical square footage then if the were above the plants and to boot try and get 12 lbs outa 4 plants any other way indoors, I have tried for years and the only way imo is lots a vertical light. If you do the math a 11 x 11 foot room is 121 square feet. 5600 watts divided by 121 is 46.28 watts per square foot, I used to run 70 watts per square foot when lights were overhead. I guess you might be able to get the same weight if you filled the room with a thousand clones but thats a prison sentence so is it overkill? I dont think so