So called zip code scanning is just rough location scanning and also uses your range settings and service types.
Oh I know Don, no argument there! You're right about that for sure. I'm just saying that because I know in my case there were a ton of things I was scanning out of the box when I first started, using basic location scanning, even after I figured out the service types, that I don't scan now, even though they're service types I do monitor, and they're within range.
Especially in really large counties, for example, you might have a lot of talk groups on a trunked system that you don't care about. Getting rid of those by pulling them out, avoiding them, or whatever, will definitely let you catch more traffic you care about.
There are a lot of other things you can do too but most of it requires using favorites lists, like setting modulation types and so on. My advice was aimed at trying to help folks just getting started be able to get going in the right direction, because that's what I think will help them most.