Zones can be scary but are simply a way of keeping the world in order. Mostly you will forget what each does if you do not use them frequently. The zone is a container for whatever connections you want to group together on your radio. Here in Florida we have the SAR net of UHF analog repeaters across the state. If traveling the range of each repeater is limited but with a full listing communications is possible throughout the state by changing to the next repeater. These are all in one zone simplifying the use of the SAR net.
Group all the local repeaters in another zone. Put all digital repeaters in a zone. A repeater can be in many zones – it is how you have every thing at your change of zones! Experiment!