Engineering is a pretty slow-and-steady profession. Best practices, tests, and robustness are part of the point. There's an argument that a good engineer would know when those criteria are satisfied and so be more able to run up to the cusp, but I don't think it is fair to say engineers necessarily (or typically) work against inefficiency. Adding more AWS nodes might be the boring, prudent choice.

Redundancy is a form of inefficiency. Failure paths often introduce inefficiency. Well defined tolerances introduce inefficiency... even though you know those motors could handle a couple extra volts...