feeding schedule

If feeding of the plants is a dual action process, the pots fill bringing nuitrients into the pots, and as the solution recedes oxygen is pulled into the root system.

This is my understanding of the ebb & flow method. Question, once the pot is filled with the solution, is it better to have an extended fill time or a short fill time. On one hand, the nutes stay in the roots for a longer period of time, does the plant take advantage of that?

Or, is the feeding not completed until the drain? If your answer, is "depends" then please elaborate.