It really depends on what you're making and if it's possible to automate testing AND if you remembered to test it. Chrome appeared to have broken full screen mo

It really depends on what you're making and if it's possible to automate testing AND if you remembered to test it. Chrome appeared to have broken full screen movie playback for 5% of users once. Something changed, perf got bad, people who previously could play full screen video on a low end machine suddenly got playback too slow to be useful. They just stopped going full screen. No bug reports came in. Nothing in the testing infrastructure caught it. I only notice because my father tried to show me a video on his atom based netbook. Similarly going full screen on a 2 monitor setup broke once. Again, no automated test. The Web Text to Speech API is broken on every browser it's in. It will work with a simple sample but start and stop it a few times and it will break. I suspect because again there is no easy way to test it. There's lots of others. automated testing is not a substitute for QA IMO.