The size and depth of a pot also influences drainage, but I’ve learned something valuable over the years in transplanting trees grown in soil contained in Rootmaker in-ground bags into 25 gallon pots. I surround the silty loam soil root balls with light potting mix on the side and bottom of the rootball between the ball and the pot, and the drainage is fine… meanwhile the soil center of the 16-18” bag holds a lot more water and nutrients than a potting mix. However, the pots are partially planted in the ground so the roots escape, but they also flourish within the pots. This combination allows me to grow much larger trees with much less irrigation. When I dig up the trees I simply save as much escape root as I can and the trees transplant beautifully.
This is my own discovery, but I doubt I’m the first to discover it. I should add that I cut away the bags before putting the trees in pots.