I tried pollen patties years ago, decided it was a waste of time and money, the bees were bringing in plenty of pollen. In my area pollen is available before nectar is so the build up of bees, though slow at first, begins with the first pollen collection, not the 1st nectar collection. Actually I believe the pollen is more important to brood chamber development than the nectar by a huge margin and winter stores is enough to feed the brood if the hive was left with sufficient stores. Cutting your harvest too close is, IMO, 1 of the primary reason people lose bees during the winter. Close harvesting induces starvation.