It's the litmus test: How much of taught abstractions do you really understand (can you adhere to the underlying coding practice without spelling it out in (costly) code? Do you really understand a runtime environment and can you make your basic tool, the compiler, optimize for your use-case?

Back then, when I was young and stupid, I agreed to develop a Command & Conquer like game in j2me with a deliverable size of max 120k. I did, but that required lot of all-nighters and a severely bruised and corrected ego..

And, as the senior dev, I got to listen to very smart recently graduated devs who did not know shit (as I did when I started). Best management lesson ever...