We’ve created required fields you must fill out before moving a deal to Closed Won.
However, if you create a new deal directly in the Closed Won deal stage, you are not prompted to fill out the missing required fields like you are when you manually drag the deal to the Closed Won stage.
This “glitch” allows reps to circumvent completing the required fields if a deal closes right away. We’ve had to create a workflow to notify reps when these properties are missing, but this is a workaround that shouldn’t be necessary.