Four types of payments can be processed through the Faster Payments Scheme:
• Single Immediate Payments
• Direct Corporate Access
• Forward-dated Payments
• Standing Orders (FPS Standing Orders not BACS Standing Orders)
Forward-dated Payments can go 7 days a week but Standing Orders can only go 5 days a week.
As a work around some banks submit Standing Orders as a Single Immediate Payment each time, however I agree with you that it is crazy and the whole system needs bring up to date!