If Ghostery is set to block all cookies and trackers, is it redundant to also set the browser to block 3rd party cookies? I've always thought so, but an article I read seems to imply you should do that. Thanks
Redundancy is always good. Extensions can be compromised and disabled by malware. I haven't seen it happen with Ghostery but I have with Ad-Block plus. By setting the browser to block 3rd party cookies, you've added another layer of security that covers the same problem. If one fails, the other one is still there.
3rd party cookies are useless and all programs that relay on lists to be updated are at some point outdated.
Some webpages do not work properly without 3rd party cookies. I let the extension delete them periodically and then there is CCleaner and similar.