My experience at $previousjob... Another issue (and argument for job-hopping/frequent job switches unfortunately) is that it's often easier to get a promotion i.e. a higher job title by switching jobs rather than going through a long and bureaucratic promotion process at the same company. (Speaking about simple promotions and not switching to a manager track.)

Trying to put together a promotion packet with items or projects that are often orthogonal to "real daily work" feels daunting. "I need an x type of project or contribution for getting promoted" - while at the same time you might feel that if the company hired you fresh, they could hire you at the next level.