There was a point in time when I recognized that in order for me to succeed at Reader's Digest I would have to learn to "work the system" that governed the place. I could have stayed but what would I get out of it? Not much. Maybe I'd have picked up some things that would be useful, but more likely I would spent months upon months learning "Reader's Digest skills."
The thing is...You can't take "Reader's Digest skills" with you. They only help you succeed there, no where else.
Now I'm not talking about general getting-around-a-big-corporation skills. Those skills are insanely important and can help you wherever you go, even if you move to smaller work environments"
Understanding the levers of power
Identifying the movers and shakers in an organization
Negotiating resources with colleagues and the IT department are all incredibly valuable
They teach you to listen. They teach you how to persuade. They teach you how to build coalitions.
Let me put it this way. You'd better learn those things somewhere, somehow in your career.
Conversely, specific skills that are less valuable include,
Mastering an arcane budgeting process that is based on historical knowledge (e.g., "That's how we do things here" mentality)
Working a proprietary IT system that exists in no other enterprise (HINT: Lots of middleware)
Catering to a single individual who is not leaving any time soon
Those are too specific. You can't take those with you.
In any situation, when it looks as though you're learning more firm-specific skills than transferrable skills, it's time to rosin up the resume.