I think this may only be technically true in a way that is unhelpful as a model for either employers or employees, and I'm not sure it's still true in the curre

I think this may only be technically true in a way that is unhelpful as a model for either employers or employees, and I'm not sure it's still true in the current day. The immediate thing that caused me to start looking for a new job, most recently, was that I had a performance review / bonus conversation that went poorly (for me). It's a little hard to distinguish whether the thing that made me unhappy was getting the feedback of "We don't value the things you want to do with your career" or getting the feedback of "and, therefore, we will dock your pay." (In fairness to them, it's not clear the things I wanted to do with my career were in fact valuable to them.) However, once I started looking, I discovered I was being seriously underpaid, and I really should have already been looking for new jobs. There's just a bootstrapping problem here - you don't know your market value until you start getting offers, and you have to start looking in order to start getting offers. With new norms about talking about pay (this very website is a good spot, for software engineers) and sites like levels.fyi, I suspect I would have come to this conclusion a little earlier, on the basis of money. It's hard to estimate your market value but you now have a better idea of what the ballpark is. (I suppose the other option is to continually be "looking," whether or not you have an active desire to leave. I know some people do that. But I personally find that exhausting.)