[nradov]

You're missing the point. Sure you can build a test to gauge whether your code meets some arbitrary level of efficiency. However the process of dynamically stepping through your code in a debugger engages a different part of your brain than inspecting static code or writing tests.

I can't offer any hard evidence to prove this. But personally I've found that keeping the discipline of always stepping through my code in a debugger — even when it seems to be working correctly — leads to improved results. Try it for a few weeks with a good interactive debugger and I think you'll see what I mean.