Please bear in mind that I was referring to redundant tests slowing the test suite. Redundant is being used here to mean unnecessary. If you are advocating more tests, each of which increases coverage to some degree, then I am in agreement with you.

Redundancy in the test suite - by definition - is pointless, and serves to lengthen the wait every time it is run, and that will multiply up and become, as I said, an issue.