You know where to look first when the numbers don't add up
Before, when the month's result didn't match expectations, you suspected everything at once: the supplier, the customer, the price. After identifying which of the three close-out pieces is incomplete, you know exactly where to look first, instead of reviewing the whole business every time the result looks low.
You decide from the record, not from memory
Before, you answered "did we make money this month?" based on a feeling about how the cash looked at that moment. After going through the diagnosis a few times, every answer about the close-out rests on a real record, which cuts the odds of deciding on price or withdrawals based on a wrong impression.
You stop mixing up personal withdrawals with store spending
Before, you mixed the money that goes out for household bills with the store's cash, making the business look tighter or looser than it actually is. After separating that piece, the month's close-out shows the store's real result, without personal expenses sitting on top of it.
You go straight to the right tutor instead of fixing everything at once
Before, you tried to fix income and expenses, personal withdrawals, and order costs all at the same time, spreading the effort thin and delaying all three. With the diagnosis, you know which record to complete first and go straight to the tutor or calculator for that piece, instead of trying to close all three accounts at once.