Most businesses don't have a software problem. They have a handoff problem. The storefront works. The accounting package works. The shipping tool works. The cost sits between them, in the person who copies an order from one screen into another.
Where the cost hides
Re-keying is slow, but the bigger cost is error. A typo in an address becomes a reshipment. A missed status update becomes a support call. None of it shows up as a line item, so it rarely gets fixed.
What connecting them changes
When systems pass information directly, the order your customer placed is the order production sees, and the status production sets is the status your customer sees.
Where to start
List every place someone copies information from one system to another, and how often it happens each week. The handoff with the highest count is usually the first one to connect.