A feast day brings an additional level to the interpretation of the readings. For a feast, all three readings are chosen to correspond to the theme of the feast. In a sense, they all go together but they do not necessarily depend on one another. Each reading stands alone and is interpreted primarily through the lens of the feast day.
For each reading on a feast day, we could ask what the reading has to tell us about the feast. And we could ask what the feast has to tell us about the reading.