The "home" websites that are available to the public feed off of other websites. When we put our homes on, for example, our personal websites, they feed out to the other websites. They only update the feeds / information on a weekly, bi- weekly or monthly basis, usually. The best way to see homes listings that are the most up to date is to have a Realtor that you are comfortable with and have them set you up with a "Portal". That is a search that you can see, through our MLS, and you can be notified via email when there is a change to your search(es). It only takes us a little time to set it up for you and all you have to do is sign in with a username and password that we set you up with. You can also mark the one's that you are interested in. It really is a cool way to watch the area that you are interested in.
Good luck !!!