> My understanding (at least where Google is concerned) is that it's a jungle situation and there's a lot of team-hopping and connection-making until you find a place to land for awhile.

I think this is only true if you want to work on something interesting. If you're willing to work in some obscure corner of ad infrastructure or Google Surveys or something and you're not trying to get promoted, you can stick around for a long time at Google and not get much done. At a big organization like Google the pace is pretty slow even if you are trying to get some work accomplished, so that provides cover for those who aren't as effective.