“If the update frequency on LinkedIn increases drastically in a comparatively short time for any given person, a job change for that person is imminent.”
I have witnessed that numerous times lately. It is easier to spot with people who do infrequent updates, but stands true for frequent updaters as well. If a job change is imminent, then the LinkedIn (or Xing) profiles get updated a lot, brushed up, spring cleaned. Descriptions get added, References and testimonials get requested. Photos get changed.
But it gets even more interesting. If several people from the same company start to work on their LinkedIn/Xing profiles, this is usually a sign for layoffs and/or change of ownership of the company.