I know this is a real touchy subject on this forum but let me throw a fact in the way of things...
Higher levels of nitrogen at the end of flower results in lower THC levels in the plants. Scientific fact.
You can grow cannabis, as if it is cannabis, or you can grow it as if it were a shrub.
General botany is great for a solid foundation, but each plant differs and there is no ONE way to grow every plant on earth.
Get specific with each plant (hell each PHENO of each plant) and you will get better results. Or you can go generic and get a generic end.
There is a reason the more you grow a specific strain, the better you grow it, you dial in...
If my leaves aren't yellowing in the last two weeks of flowering, I fucked up and have too much nitrogen in my soil.