Honestly, I'm still on the fence about what acceptable code coverage is. There's people who claim 100% is ideal, others (like DHH) think aiming for 100% is detrimental. My company is at 89% right now, which I think is commendable for a codebase of our size (100k+ lines), but how do we really know? Acceptance tests can cover broadly without needing to test every line of code, but if that gets the job done, what are you really achieving by improving that number from 89% to 100%?