Should be providing critical levels of p and k around roots the entire time.
There is more than 1 study that shows amping these things up in flower or even the entire time is not actually causing any differences in yield or potency once over a certain threshold. Proof is in the pudding, or lack of proof in this case.
P and K enter the plant through active transport more so than the other nutrients. This means when the plant needs it, it grabs it. this is why it's not so much about a high concentration but merely the "right" concentration so that it is easily availble and going above that provides zero benefit.
it's one of the many things people have done and repeated without any proof of concept or any attempt to prove it helps, Like the obsessive need to flush before harvest even if the plant is perfectly healthy, that coco coir needs more Ca, 48hours of darkness, burning it, icing roots, etc etc... just a bunch of madness out there.
