Some subscription stores do everything on a schedule. As an example, I subscribe to The Simple Jar. They deliver food weekly on a Monday.

They get all orders on Thursday, prep them on Sunday, and deliver on Monday morning. For businesses like this, for example, monthly loot boxes, that have a particular schedule, synchronizing subscriptions is hugely helpful. Customers can subscribe whenever and they'll get the next shipment and their payment will be postponed until the next billing cycle.

Check the Align Subscription Renewal Day checkbox and then follow the instructions under Learn More to enable this feature.