Why the vegetive steering from days 22-42? Why not the generative steering throughout flower/bloom?

Steering vegetatively in mid bloom helps the plants to bulk up by pushing a constant fresh supply of higher EC feeds and dissolved oxygen through the medium. At this stage the roots have filled up a good portion of the pore space in the medium that once stored water causing the growing medium to have a lower water holding capacity (WHC). Therefore you need to water more frequently to prevent drying back too far and burning the plant.