For the record i would still train/defoliate in a vertical system.
Vertical growing is all about efficiency, more usable light from less light sources. 2 600s are ideal, or a 1000 for tops and a 600 for lower.
Heath Robinson claims he yielded 4lbs from 8 Mr.Nice Shit strain plants in a donut around 2 600 watts lights, 1.493 grams per watt.
You place a box fan at the bottom of the lights and blow the hot air straight up away from bulbs, heat rises away quickly.
Bulbs emit light in 360 degrees and the farther the light travels or has to be reflected the weaker it becomes.
In an empty room an overhead 600w hung in the center of a room has an effective footprint of 3x3 right below it.
The same 600w hung vertically in the center of the room illuminates a 3x3 footprint on every side now instead of only on the floor.
We are talking about circular vertical grows
Plants put all their growth towards whichever side has the light.
Putting each plant the same distance from the bulbs arranged in a circle/donut allows each plant to be encased in maximum lighting from top to bottom and all through the canopy.