From some Australian research it is interesting that bees just collect pollen, they don't discriminate for quality, if maize/corn pollen is available and easy to get they will collect it in huge amounts even though it is low quality.
Also personally I have found that even though you can offer a high quality pollen substitute, the bees will ignore it. Even if there is a small amount of natural pollen coming in and you think they need more I have found they still ignore the substitute pollen. I have not tried pollen patties only dry pollen substitute.