4 years seems like a long time, but I'd easily say that's true for a year. I suppose it's relative to your definition of good.

In my industry, 2 years is about what it takes to feel the ramifications for your bad decisions. Leaving before then makes you a bomb thrower in my not so humble opinion, leaving everyone else holding the bag. And unless you are a contractor, it's a resume red flag for me.

I get that not all jobs work out, but a long string of < 2 years makes me skeptical.