The noon period is not as good as the other two except on dark stormy days. Puddle ducks tend to feed at the crack of dawn. Divers are a little later. Ducks in migration however, may be stocking up for the long flight in from the north. In this case they may eat anytime of the day or night.
Ducks do feed every day.
Just because you don't see any where you are, don't assume there are none in the area. Move and keep moving until you find them Ducks fly lower and move around more on cloudy, windy days. Warm, still sunny days are usually poor days for hunting, except during peak periods of migration. Ducks migrate by the calendar as much as by the weather. Early to late freeze-ups may affect the migration, but the major movement of each species will usually come within the same week or ten day period.