People often dread tests because they don't want to fail. Failure means you'll have to take the test again, after you've spent even more time studying or working on your health.
Email testing is different.
The likelihood of failure is higher when you don't test. You won't get as many opens or clicks, and you definitely won't learn anything about your audience and how they view you, your content, and your organization.
Continuous testing and learning is needed for ongoing success in email marketing. Whether you’re using a simpler A/B approach, where two versions of copy or design (version A and version B) are compared to one another, or a multivariate testing strategy which compares a higher number of variables and reveals more information about how these variables interact with one another, the critical point is that you should always be testing.