On the surface, test plans sound like an excellent idea. For instance, here’s the definition of a test plan taken from Wikipedia: “A test plan is a document detailing the objectives, resources, and processes for a specific test for a software or hardware product. The plan typically contains a detailed understanding of the eventual workflow.”
This definition covers what most testers and QA departments would want as part of their organization. Everyone wants a single source of truth documenting the project’s goals and the necessary steps to get there. We all want to have a comprehensive understanding of the work that needs to happen to get results, feeling that we’re on the same page.
Unfortunately, the real world doesn’t work that way. Despite our best intentions, most test plans are a burden on the team at best or an utter waste of effort and resources at worst. Of course, plenty of organizations are successful with their test plans, but I’m willing to bet they’re the exception, not the rule. Creating a test plan requires lots of work and long-term thinking to make it useful during the project’s lifespan.
Source: Do You Really Need a Test Plan?, Dennis Martinez, https://dev-tester.com/do-you-really-need-a-test-plan/