When I operated a fruit-tree-selling nursery business, I incremented pot sizes from 1, to 5, to 15, and then 25. Hopefully they sold at 5 gallon because 15 gallon is more maintenance.
Beyond the needs of nurseries and into my own yard, I go straight from 1 or 5 gallon into either the ground or a 25 gallon. My opinion is that incremental pot size upgrades is not the best conditioning for roots.