Bill,
There are several ways you can set your scanner up. It really depends on how you want to listen and the number of systems that are in your area.
With the DMA of the 996, you have quite a few options.
What I've done with my 396 is organize by locality or system (I'll explain this in a minute) and then using the sub banks to split into services.
So for me, quick key 1 is my local multi user system. With four jurisdications using it, it is taking all ten sub systems quick keys to handle this. I have police and fire for each jurisdition in their with their own sub key. I also have special events in their own sub bank.
Quick key 2 is the neighboring city trunked system. Again, I have broken it down to police, fire, an Army fort that uses the system for their security/fire and some special events.
The same holds true for each of my other systems. The further away from home, the higher the assigned quick key.
I also have specific quick keys for state police and other wide area services (like the national park service in the area).
Now others use different organizations. They may organize by putting all police in one key, all fire in another, etc. An issue here is trunked systems. As already mentioned, you cannot put multiple trunked systems into a single 996 system. But you can assign a multiple trunked systems to a single quick key.
Others just group by location and do not subdivide, just entering the talk groups or for conventional, the frequencies they want to listen to.
So the thing is to take some time and think about how you want to listen. What with 99 (at least that is what the 396 has) possible quick key assignments, you have a lot of capability.