coco tastes better
In comparison to chewing up a rockwool cube it's probably easier to swallow Coir as na rule needs more stuff to get set up growing in hydro so when they go the shop the guys chat enough sh*t after all it's their job to sell more stuff than needed & not give tip's. That's illegal. I'd sooner throw out a few cubes than all them 20 ltr pots worth of coir & bring in more bags for 2 lamp commersh.
For anything over 2 lamps upto 30 lights I'd use the same plant numbers but change the game rules..
When you look @ it like 8 plants can yeild what a few hundred would it's a no brainer 8 plant grow is the rule of thumb, over 27 & your in the next bracket