It is possible to maintain a delivery calendar for each vendor. However, this calendar does not take into account that the transport days refer to working days.The calculation of the receipt date is always based on transport days (Purchase Transport Days) and the "Open Days" in the Shipping Calendar.

Example:

A supplier needs 3 days to deliver. However, no deliveries take place on Saturdays and Sundays. So if the shipping date is Thursday the receipt date is Tuesday.

The delivery calendar should work differently and the working days should be maintained via "Open Days" and the delivery days should be assigned via the "Closed for Pickup" functionality.