If you are growing indoors then you are interested in per square meter not per plant. You can replace one big plant with nine dwarfs in the same space. Having slightly too small pots is good if you are trying to stop them growing too tall. You don't gain anything by having the canopy higher, you have to move the light. The energy that the plants spent building those long stems could have gone to bud production. The ideal plant would be flat so as to capture the most light at the perfect distance with just the cola sticking up, like the SCROG grows.
If you start drilling holes half way down you get the air-pot effect without the problems of the water running off the sides when you water them.