I thought you had mentioned something along these lines awhile back. An idea or theory that the plant picks up what it needs, stores it, and makes use of it when flower starts, and then lets all the extra just sit in storage in the larger fan leaves so it can be returned to the soil during the non-growing season when the dead plant is decomposing.I just read this:
“The researchers found that hemp plants front-end load P during the first half of the growing season as seen with the plant’s upward accumulation of P. At midseason, the total accumulation in the plant plateaus. This indicates that the plant uptakes limited additional P. Hemp relies upon those internal P reserves and translocates (moves) P if it is required in other parts of the plant.
This suggests that adequate P levels should be provided to cannabis during the first half of the production cycle for the plant to accumulate an adequate reserve that can be translocated if needed later. Providing a P boost late in the growing season appears to not be needed. There is a need to conduct a scientifically based trial to clear up this uncertainty with greenhouse-grown cannabis.”
The 'front-end loading' is similar to what I think the plant is doing during the vegetating stage with the Nitrogen and Potassium. The nutrients are there waiting, the plant takes what it needs, and if enough is stored the yellowing and dyeing off of leaves is minimal until maybe the very last week or two of flowering.