A marketer has built a journey that they want to run multiple times a day...

To run a journey multiple times a day based on newly compiled data, the marketer should set up an automation to populate the Entry Source Data Extension. This ensures that the latest data is always available to trigger the journey. The automation can be scheduled to run at the desired frequency, ensuring the journey starts with the updated data. Salesforce Marketing Cloud documentation on Automation Studio and Journey Builder entry sources provides detailed instructions on setting up and managing such workflows.