Why is it taking so long to go into full flower?

Indoor Growing
10

I’ve always wondered about 12/12 from seed for small plants. I always thought you’d get a decent amount of plants that get stretchy. Just constantly trimming plants from seed down and shaping them the way you’d like before flip or flipping small mature clones are the two I know that work for keeping them small. I prefer mature plants or clones going into flower personally though.