I forgot to mention, my experiences are all based on EU countries. When we worked with US companies, we would occasionally joke that a 2 year tenure is considered long at the US companies we worked with. There would be people joining / leaving their teams every single month.

In the teams I've been part of, average tenure at the company was over 5 years in every single case. In one case over 15 years.

These are all development positions. Management positions and marketing positions did tend to move around a bit more often.