This applies to enterprise software as well. I was an architect for a large CRM project with Siebel and software from a company called Yantra (acquired by Sterl

This applies to enterprise software as well. I was an architect for a large CRM project with Siebel and software from a company called Yantra (acquired by SterlingCommerce). The difference between the two? Siebel "bolted on" an API layer and Yantra consumed their own API for internal, core functions. The difference was night and day. As expected, the Siebel API was practically useless. Yantra's was rock-solid. No better way to make sure your API is solid than to use it internally.