Lots of variables. It'd be even better to see HOW they are setup.
A big thing I find is being able to see WHAT HAPPENED is one thing, being able to see WHO DID IT is something else.
Many home setups can see what happened but cant ID who did it. Review some of your old footage, can you make out faces? If not, I'd start there.
Watch how people approach the house (even just package deliveries), are they facing away from the cameras? does their hat prevent you from seeing their face? are they looking down (most people do by default)? etc..
Check out the
Wiki and see if you are making the common mistakes, mounting them too high etc..