I haven't read up on it yet, but just Googled it and there is plenty to read.
I usually veg with t-5s. With t-5's, you can control stretch by adjusting the height. The LED's also have an intensity setting from 5 to 100% which complicates control. For instance, you can get similar ppfd at the canopy from 50% @ 12 inches, as you can from 75% @ 18 inches (just an approximation), but depending on thickness of canopy, penitration will be different between settings.
I probably should work @ 50%, noticing the effects at different heights, before learning how the different intensities change the effects on the plants?
I started the seeds for my Outdoor Tent grow late in February. Knowing it was gonna take time to sex and reveg, I was able to keep them short by running 25% to 50% nutes, higher distance with the t-5 light, topping, pinching, LST.... etc.
In Flower (outside), you can see the difference between plants grown in a shaded environment or direct Sunlight. You can see a Huge difference in growth and Budding from all those Incredible grows we have in Cali vs mine.
Knowing how to Tweak the light at different stages to influence growth is just as valuable as knowing when and how much to Defoliate to control the plants growth and structure.