Sas, I think it depends on the individual shelter how often they update their websites and Petfinder ads.
I have looked at the cats from my local Humane Society at Petfinder and then looked at them in person at the shelter and
obviously some of the kittens that were on Petfinder are no longer available while some of the older cats are there for months.

Oh and if you are serious about looking for a new cat or bunny I can be available to help you with that!