After the Jagger farce, I completely built a new site to replace an old one which was defunct due to all pages being supplemental due to session ID problem. The new site was fine, and then more and more pages were dropped until only the index page left. I removed the site from Google with the removal tool and replaced it. New site was duly crawled and indexed fine. Within weeks most pages have gone supplemental - the problem not mine this time - instead of showing the correct meta title and description tags, Google has merged together page content to make title tags, including the home page alt tag on every page. I give up.
My personal experience thus far with several sites is that once a page has gone supplemental, googlebot never touches it again, however much you update it (cache on pages of the last site was over a year old and never updated).