I think static object analysis is dependent on the user/camera needs.
For example, I have a couple of cameras that cover my driveway which can have a couple of cars parked in it. On those cameras I am tracking person, car, truck, cat, and dog. Without the static object analysis if there were was motion, like a bug flying across the camera, it would detect my parked cars and trigger an alert on the cars. So in that case I have detecting the static objects turned on to prevent false positives. This was a real PITA with some previous versions of BI where it wasn't working correctly. You may also want this if you have a camera in a garage with a parked car that may have motion such as a bug (especially if using IR which can attract the bugs).
Conversely, on my backyard and indoor cameras I do not have any static objects that would trigger so I do not have it turned on for those cameras. Oddly enough, there was a stuffed dog in my living room once that would trigger when the shadows caused motion (large window with lots of sun). So again, you have to evaluate based on your camera's situation.
One last thought is just how many cameras are configured for static object analysis. If only a couple (like in my case) you shouldn't be flooding CPAI. If you have a lot of cameras configured (like a parking garage) then you will have a lot traffic for CPAI. I would say turn off and see how many false positives you get to determine if you need it.
