I run a couple of sites for my company and I just wondered why some sites get cached about once every 10 days while others have cache dates that can backtrack as far as a year. For the sites with cache fluctuations, I know that they have been knocked off the SERPs, but some weeks I check the cache date and it is not found, other weeks the cache date was recent (within a week or two), and other weeks the cache has been rolled back as far as 10 or more months.
Why does Google do this? What does it mean?
