I think it is a mathematical thing; not a biological or agricultural thing.
Every clone needs its space to develop.
Let's say 2 inch x 2 inch
In greenhouse where they cut clones, they have trays above each other.
View attachment 4511569
So if you would have a tray of 20 inch x 40 inch you could theoretically have 10 x 20 clones = 200 clones.
3 layers is 600 clones.
Of course you need some extra space but with 25 inch x 50 inch it could be possible.
In the pic you see that they have at least 5 layers.
3 layers in a room of 6 feet would give you 2 feet per layer. Plenty of space for longer roots.