The main uses of Zones is either separate buildings on one site, or, from a health and safety perspective, different risk areas within your building.
Having separate buildings is clearly a risk as an emergency is unlikely to strike all buildings in the same way, so knowing who is in which building is essentially, especially as they are likely to have different muster/evacuation points.
Having separate areas within your building is also essential if those areas present significantly different risks, obvious examples being a laboratory, manufacturing floor and office in the same building.
The way we manage zones is that when you sign in initially, our visitor management system simply signs you in to the building you entered via, from then on, when you move between zones, the system signs you out of the old zone and into the new zone at the same time, so you are never in more than one zone at a time.
You can move around as much as you like and admin users can see where all people are on site via our self refreshing security user pages.
When it comes to an emergency, the designated staff can view your evacuation lists on smart phones or tablets without having to install anything. They can view a single zone or, if numbers are small, all zones on a single page and people who need assistance are highlighted so you can make sure they are supported correctly.