What size can I expect in a

Hey all,
I was wondering if there’s a general rule of thumb when it comes to plant height & pot size. These plants started in 1/2 gal pots, moved to 2gal, and at the present I have 18”-ish clones in 5gal plastic pots under t5’s, in a few weeks I’ll be moving them outside to take advantage of the sun while also transplanting them into 10gal smartpots.
Last year I went from 1/2gal to 2gal to 20 gal smart pots. They grew to about 8-10 feet after I topped them 3 times. The problem I noticed was after the season was over I took the medium out of the pots and the root structure wasn’t filled out within the smart pot. Basically I had the root ball from the 2gal and water roots all below 1/8 of the pot. They didn’t fill out like they did in the plastic pots. This year (second grow ever) I’m trying to build the root structure up more before moving them outside and into their final home, hoping to have a larger root structure.
Does anyone have experience with different smart pot sizes and what I could expect with the changes I’ve made this year?

Of course, but say I have the same strain light food etc as last year. Do you think I’ll have better results using the 5gal to 10gal vs 2gal to 20?
Thank you for your response @WickedAle.

5 gallon is the smallest I would use on plants you expect to grow for 6+ months.
10 gallon should do well. However, if you have 20 gallon that should be more rewarding.
suggest you not keep in small pot too long. helps if you break up the root ball just a little.
that signals the plant big changes happened and it can grow bigger now.