This ^^^^^^It sorta the dark secret of led. Lots of commercial grows have failed cause they didn't know how to use them properly.
HPS and CMH. You can use a lux meter. To measure intensity.
Led u usually need to use a more expensive par meter for to get accurate intensity readings.
I personally like led myself. But u sorta need to understand how they work. Cause u can easily burn your plants. If don't know how much lux or par a plant can take at each stage of growth.
The intensity also fades, very fast at a distance. Vertical space, is very limited with led's.
Light is all about, a grower's needs.
Thats why i use HID. Its great for vertical space.
Ive found LED only very effective, for the first foot, or two.
I love Christmas trees. I cant get this with LED's