My experience is in the context of payments - when charging someone's payment card, check whether it's one we've issued and just run it as an internal balance transfer rather than run it through Visa (read: free). When doing the whole "build fast, iterate quickly" thing, it's easy to forget about such optimizations, especially when it's a relative edge case and works just as well if you leave it alone (arguably better, since there's less conditional logic in the code)

So by "network" I more meant database (i.e., network of users).