maxing growth using rock wool question

I grow very simply using 4x4x4 rock wool cubes. sometimes 6x6x4's.I just water every other day til they nice and wet and let them do their thing. 3ed grow now, very successful with last 2.

I know from a little experience and reading that your plants can become root bound in pots and i assume this is the same for rock wool cubes. I have always kept my ladies short and moderately small in the past but i would like to MAX their growth potential this time around.

1) How do I know when they have reached their max in veg?
2) Can allowing them to max out in veg have negative side effects later in flower? 3) Whats the longest you suggest to keep any plant in a cube start to finish? 100 days?

Any feedback or advice is appreciated. Thanks.

1) there is no max, you can veg for years if you want. But they will be mature at around a month old, excluding the seedling stage of 2 weeks.
2) no, just light might not penetrate all the way through. Thats where side lighting comes in
3) I dunno, usually the cube falls apart due to watering before that happens. I don't think there is a maximum date, people grow trees and stuff hydroponically.