I have been running coco for many years now. When I began I went overboard on getting my runoff. Now I have changed my methods some.
Depending on growth during veg, I will water to runoff for each cycle but one cycle i will set extra time to make sure I good runoff.
During flower, let's say I am doing 4 cycles per 12 hrs lights on, I set first cycle to get a decent runoff, the second and third cycle do not get good runoff but do get some. The final cycle i add extra to get very good runoff prior to light off.
This has worked well for me, though it does require me to be a bit anal and hover over my plants like a hen hovering over her chicks.