My thought is that wherever the root is headed based upon its configuration, whether for lateral or longitudinal growth, it will succeed at that and the only stoppage occurs at hard surfaces, whereby they continue on once past the obstacle, just like a Roomba, butt more assertively, IMHO. Rootba?
In MY case at the moment, all noteworthy root growth has stopped in MY experiment since I added MG 18-18-21 Tomato Food. HS, yes? I'm thinking that if the plant and roots are fed-up they do not have to forage further, giving credibility to that phrase "...every 7-10 Days' as a schedule of how long this takes to clear up, in the Patch. Hmmm...eg