There isn't any reasonable number because numbers mean nothing. As an example, last time I did any serious pull up training was way back in 2017. At that time I was able to do 15 pull ups with a very strict form, chin touching the bar at every rep. If I tried doing that now I wouldn't be able to do it and that doesn't mean that I am weak or unfit. It simply means that I lost some adaptation in that particular exercise. Pull ups is all about practice and adaptation. The more you do them the better you will become. Most people cheat and do pull ups wrong, then inflate their numbers to make themselves look impressive when in reality most of their reps don't even count because they're done with a wrong form.