A few years back I added 2 below-canopy lights because the top half of my colas were always so much beefier than the bottom half. i lollipop or trim everything below the SCROG so there’s unimpeded light from below. The SCROG keeps most of the leaves from dropping, but there’s an oscillating fan below canopy that blows any leaves off the lights just in case. Both my colas and my yields have grown over the years and I attribute some of that to the lower lights. This set-up produces such a thick canopy so I harvest in 2 stages. First I chop down the most exposed & ripe colas & leave the rest (the greener colas) to bask another week or two, now with far better exposure to direct light.
When I 1st started growing in this tent, I would pull about 2lbs per grow, but now I average between 3-4lbs.