Hi and welcome to the site! I split your question out to a new topic because it’s a new question (helps people searching). Also coz I’m a control freak lol.
From memory IE checks for an updated version of the xml site list something like 90 seconds after starting the browser. As I mention in the previous article, I’m not working in an environment that uses IE Enterprise Mode anymore, otherwise I’d do some testing and let you know. I don’t know how often, or if it checks regularly thereafter.
I believe that an XML site list is cached in the users profile and a version number is cached in the users registry. Gotchas to watch out for if you’re doing funny stuff with user profiles, like profile management such as VMware User Environment Manager.