"These test suites are often 5-10 times larger than the actual submitted code, and it is difficult to imagine anybody outside of this type of environment spending so much extra time designing (and testing!) test suites with 100% coverage."

Try the (extensive!) programming challenges at http://uva.onlinejudge.org/

In almost all of the challenges the example input data is sized such that even the most naive algorithm will run within a second or so. When submitted the code is judged against much larger/more-complex sets of input that will catch out inappropriate algorithm choice, unhandled edge cases, etc.