1. One person knows the file.
If the file goes down with that person’s laptop, the business goes down with it. The hidden cost is risk, and the obvious cost is the conversation that starts every time they take a vacation.
2. Two systems disagree.
The website says one stock number. The floor says another. The spreadsheet has a third. Customers find out at checkout, and you find out from a complaint email.
3. Closing the books takes the weekend.
If month-end means a Saturday at the laptop, the system is no longer serving the operation. It is the operation, and it is winning.