I don't know if roots are always growing or if they have a point where they stop. But what I do know is while my plant is flowering and budding the roots are constantly growing and latching onto my auto watering wicks.
It's all about hormones in the plant, the roots will start to blow up again once the plant goes back into veg in 4-10 weeks. Depends on genetics and the care they receive. I just revegged a couple different plants and when I took cuttings off the reveg they blasted out gnarly fishbone roots within 10 days of putting the clones in cups. My reveg plants took a few months to fully recover and grow out enough to take clones off them.