And for anyone who might not have time for that now, here is a summary of some of the basics from farside's thread:I suggest that anyone who still thinks that P needs to be boosted during flowering read his journal in its entirety.
This is a pdf with plant analysis charts and graphs (with full detailed lab analysis) done on the macro and micronutrients found in three different strains of cannabis plant during veg and flower.
The varieties and analysis are from 2003, but I don't think we have modified the plant in the last 17 years to the extent that the nutrient results would vary that greatly today. Here are screenshots of the first three graphs:
Besides showing how little phosphorus the plants are using compared to nitrogen and potassium, they show the continued need for nitrogen in flower.