[GFischer]

"Quicker way to get promoted at large corp - prove your skills, leave on good terms, gain visibility and titles elsewhere and then re-join large corp at a much higher position."

That one irks me no end, but it's in my experience true. Also, in smaller companies, "title inflation" is a thing, I've seen companies you can get named whichever job title you prefer in exchange for a lower or no raise in salary.

And afterwards, said employees spin their "inflated" job title into a better job at large corp. (which they usually are qualified to do, but they have a leg vs equally qualified internal employees with a lesser title).

Edit: my experience applies mainly to NON software large corps., which have less ways to gauge the skill levels of internal employees in IT. Also applies to the government sector (same as credentials and certifications).