A few years ago the computer would skip over any app that wasn't updated within the last 6 months or had an expired passport/medical. Maybe they changed that but I doubt it. Whoever has access to airline apps at United could theoretically take a look at any app. The chiefs used to do that during meet and greets at CAL. If the computer can't select you because of expired whatever it is going to severely decrease your odds. If you have the pull to get your name in front of the right people I am sure they can expedite the process outside of airlineapps but that person probably had an updated app.

As for the length of having your app in I don't think it matters. They do like to see letters of recommendation and they never expire. It looks good to have some older recs that shows them that you have wanted to work there for awhile.