I had one professor who used private (30%) and public (70%) tests. You could iterate on the public tests up until the submission deadline. But you never saw the private tests until the professor ran them on your program after you submitted it.

I think this was a good middle ground that forced you to think beyond the rigid parameters of the public tests, and discouraged things like “switch” statements.

Quality of code was also a component, as determined by a TA.