Does your AI-built Excel schedule account for holidays?

Before sending a client a delivery date from an AI-built spreadsheet, try a week when your team is closed for a holiday. Microsoft's existing Excel guide says WORKDAY excludes weekends and dates supplied in its optional holidays list. A formula such as =WORKDAY(A2,B2) has no holiday list. Using the right function name doesn't mean the sheet knows when your office is closed. I'd ask the assistant to show the start date, the number of working days and the holiday range behind its answer. Then count through an ordinary week and a week with a known closure, comparing the sheet's dates with the calendar your team actually uses. Agree which calendar the client promise follows before sending it; a customer's public holidays may differ from yours. This is a check suggested by the documentation, not a failure I've reproduced in an AI product. Keep the calendar and its year visible beside the calculation, so the next person can see what the date assumes. A tidy schedule isn't much help if someone has to work a day off to keep its promise.