You also have to qualify 100% coverage: SUT lines, branches, or paths? Those are all very different levels of rigor. The two most useful code coverage stats I'

You also have to qualify 100% coverage: SUT lines, branches, or paths? Those are all very different levels of rigor. The two most useful code coverage stats I've found are 0 and "less than yesterday." The former tells me something pretty important about the culture of the team who owns that code; and having rules against the latter is about the only way to ensure a test-on-checkin policy.