Unit tests are a tool to solve a problem. If you don't have the problem, don't use the tool. If you can do major refactorings without impact on productiviy, do

Unit tests are a tool to solve a problem. If you don't have the problem, don't use the tool. If you can do major refactorings without impact on productiviy, don't have a QA department doing manual tests, junior developers can deploy to production with confidence on their first day and customers are happy about the quality of your product, don't solve a problem that isn't there.