As people have already said, I don't think it's useful to state the number of expected logs in the log book since a log may take up too much space (stamps, stickers, etc) or less space (several cachers logging with a team name).
What would be useful, though, is if the "Needs Maintenance" page could report on a separate tab how many Found logs each of my caches have received since my last Owner Maintenance log (or publication, if there are none). When I replace full logs I write an OM log. If I visit one of my caches and don't replace the log I try to write an OM log anyway to note the status so that I know later how full the log was.