You will get faster root development if you leave your buckets half empty. Leaving the root mass above water with the tap roots in water will promote root growth as the plant strides to access the water supply.
Also the more roots exposed to air getting water droplets on them the better. More Oxygen means faster feeding and eventually an affect on yield.
Fill a plant A with 4 gal of water on day 1 and leave it until empty.
Fill plant B with 2 gal on day 1 and 2 gal once water level is low.
Bet ya find the lower water level leads to faster uptake, especially pre flower