Avoiding the rabbit hole of horizontal scaling

It is important to the 80/20 rule and the rule of threes in mind. We do not want to try to support 80% of the popular browser and operating system combinations when our customers are using only 20%. It may sound pro-active to try to support Safari on Mac when our customers only use Chrome on Windows. Attempting to do a regression test in a new browser on every environment becomes logarithmically impossible. You may not have the time to execute all test cases on all browsers and all environments. We only want to test on the browsers that are used by more of our users, so that might be a maximum combination of three: one browser in two operating systems or two browsers in one operating system. In addition, time can be taken away from creating new tests if we are trying to determine the root cause of why one test runs in one browser or operating system and fails in another.