Summarized payment date (in automate vendor payment proposal) should be possible to use when Period field is set to Invoice for the method of payment.

Summarized payment date – as of now

"The summarized payment date is used only when the Period field is set to Total for the method of payment of the invoices. If the Period field is set to Total for your methods of payment, you must set the Define summarized payment date criteria option to Yes. If this option is set to Yes, use the Number of days adjustment for summarized payment date field to define the summarized payment date as the specified number of days before or after the date when the process runs. The number can be positive, negative or 0 (zero). For example, the series generates payments on Wednesday, and the company wants to create a summarized payment on Wednesday. In this case, set the Number of days adjustment for summarized payment date field to 0."

It would be important that this would work in any payment of method because many companies have cross border payments, and the Period field is set to Invoice for the method of payment.