Ok, let me reply simply - yes, you can program all the sites into one bank - but most scanners will only listen to one control channel at a time (unless you use the trick of interlacing conventional freqs with control channel freqs which personally I don't think is a great idea).
You should listen to the site with the traffic you want to hear. Not all sites have the same traffic.
What you should do is read this here very carefully:
http://www.interceptradio.com/wiki/inde ... MonitoringIt was written by Wiz, the network manager for the KCTRS. It will explain everything you need to know about what traffic is on what site (i.e. smartzone and smartnet operation)