12" light height is to close IMO. The manuals that come with led lights that show recommendations for height and intensity are often way too much.
Seedling stage - I run at 36" height, 20% intensity
Veg - 30" height, 30%-40% intensity. Let plant grow to 24" and move light back to 30"
Flower - I stay at veg settings and after a few weeks start increasing intensity until middle of flower, let it ride at higher intensity for a few weeks and start lowering intensity again toward harvest.
I also don't like to ever have my lights closer then 18" in flower, flipping at the right time for photoperiods so you have plenty of head space for the stretch is important.
The higher your light is over your plants, the more coverage you will have. Think of it like shining a flashlight at a wall, as you get closer the beam (area it lights up) gets smaller.
If your light has to be closer, lowering intensity will compensate.
In my 8x4 tent, instead of moving the light all the time I decided to keep it at the top of my tent and adjust intensity only throughout the grow.
Moving lights all the time can be a pain so if it works out well in my 8x4, I will do the same in the other 2 tents.