I think that with what ive heard yes, I can believe cannabis probably does use more K than P during flowering. But TBH unless your a complete idiot, you can grow unbelievable herb with pretty much any nutes available on the market, so it's not exactly a game changer.
Infact, ive heard lots of talk about you have to have this suppliment and you have to have that piece of kit etc, and to some extent yes you must buy some expensive kit if you need to, in order to maintain that ideal environment. But so long as you are able to provide that good environment and you grow with good genetics you cant really go wrong. I grow in coco and am damn sure that PHing the input solution does next to nothing to control the PH thats going on in the coco itself, still I do it ofcourse. But I bet that really it's just adding unneccesary P into the pot just for the sake of the few seconds that it will stay that PH once I pour it in the pot lol!!!.
Also while im at it, ill talk about vegging plants. You can do what ever you like with vegging plants. My vegging clones go through all sorts of hell before making into the flowering tent. right now they have completely overgrown the veg cab and there is some really lame growth on them and burnt tops etc from the T5 lights.
But as soon as they get hooked up to the drippers under the 400w MH lamp in the flowering tent for a couple of weeks. I trim them up good and they go off like a rocket to 12/12.
I suppose what im trying to say is that you dont need to baby your plants to hell and back. And worry if nutes need more K than P, cos these things thrive given a good environment full stop, they grow like weeds hence the name. scroggsy.