If you're talking about something like a Super Spreader, I tried them and took them off within a day.. The idea is to reduce heat directly above the plants where in theory you could put the lights lower. It may work, but did all kinds of weird things to light distribution.

Adjust-A-Wings :: Super-Spreader :: lighting for indoor plant growth

I do like Adjust-a-Wings though! Used to run 2 x 1k lights with big octagonal reflectors called Sun Soakers.. way too hot. Swapped out for 3 x 600w with adjust-a-wing mediums and I'm getting much better yields due to better light control and it's much easier to manage the temperature.

Peace,

Farmer Rich