This isn't an experiment that can be run both ways, but I find it seems to work. I've been here 13.5 years, starting from about 5 years of prior experience. Increases are irregular, but look to be about 7.3% compounded per year. Note that the earliest years of my career are excluded, which is when you'd expect to see the largest increase.

I've never seen layoffs. A person who regularly moves on is quite undesirable, because they would leave before being useful. It typically takes a year before we can really put somebody to use, and two years isn't uncommon.