Using a test plan adds structure and accountability to your QA cycle. You know exactly what was tested and what’s working; but, more importantly, you know exactly what’s broken. Test plans can be as high-level or low-level as you need, but having one is critical to ensuring your application or website does what is promised. Having a test plan in place, ready to execute at a moment’s notice, also means that you have a great metric to analyze build progress – you have a set number of test cases to run against each new build to make sure everything is still working as the code changes. Tickets can easily get closed out and buried, but with a good test plan in place those issues get reopened and noticed.