The delegation in Zechariah 7 was concerned with the correct date for a fast. God was concerned with their treatment of the widow and the poor. This is the recurring heartbeat of biblical prophecy: external ritual is worthless if it does not produce internal transformation.
Jesus echoed Zechariah when He rebuked the Pharisees for being meticulous about tithing mint and dill while neglecting "the weightier matters of the law: justice and mercy and faithfulness" (Matthew 23:23). The New Covenant is not a list of new rituals; it is the fulfillment of the Law's original intent—love for God and love for neighbor, empowered by the Spirit.