The most typical time for an update-listing suggestion is "never" -- that is, most suggestions turn out to be not useful (for one reason or another).
[Note: understandably, if a suggestion is substantially and obviously not useful, an editor may not go to any extra effort to see if there is SOME useful information down under all the hype. (That is, a description saying "world's greatest and most artistic photographic representation, photographs, pictures of an extremely cute and friendly albino mouse" might reasonably be deleted out of hand, even though the current ODP description incorrectly says "pictures of a _spotted_ mouse".)
Another typical time for an update-listing suggestion change is "less than five minutes."
Anything in between is also "typical", depending on factors that are too numerous to be listed, and too random to be predictable.
There's no useful way to speculate about when a single action might take place. It's rather like saying, "How long is a typical piece of string?" Because the only reasonable answer is, "Not quite so long as it might have been, but longer than it could have been."