Height Of Lights Of Some Grow Rooms

Hi guys, I keep on seeing big grow rooms where the lights seem to be 2-3 meters over the conopy, I think this is about 7-10 feet.

And on the opposite site are the home grows with a few lights which are only 2-3 feet over the conopy.

So do you have any explanation why most of the big grows have their lights so high?
 
Gravitas in flowering.

I've checked PAR tests and can't imagine even with the overlapping of the many lights that there is sufficient PAR over the plants. Oddly enough their plants seem to be in good shape and not stretching.
 
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