What is a reasonable time limit for tagging a page incomplete or no effort?

[MT2008]

Originally Posted by BurtReynoldsMoustache

Perhaps a {grandfathered} tag is in order? To indicate that though a page is technically against the rules, it has been given special recognition.

This is a really great idea. People keep asking us stuff like why we claim documentaries are not allowed even though we've left up some pages that predated the rule (and which took enough effort to make that deleting would seem unfair). I'm all for this.