Ben Framed;
Honey bees don't collect pollen based on it's nutritional value, they collect what is available. When it is brought into the hive and placed in cells it is eaten by nurse age bees. Any not eaten immediately is stored and used when fresh pollen is not being brought in. The bees prefer fresh pollen over pollen that has been stored as bee bread.
Patties are eaten immediately and is not stored the way pollen supplement fed dry outside the hive is. One reason patties are eaten immediately is the sugar content makes them attractive to the bees.
To know if pollen supplement is needed do as Troutdog says, look at the amount of food around the very young larvae.