Geofences are not accurate. It’s device dependent and you need to move at least a couple of meters in order to trigger a change. In case of an iPhone, you might even need to move a couple of hundred meters. The radius of a geofence should be at least 50 meters. With testing we had situations where a geofence threshold could be up to another 50 meters. So, it’s not advisable to have multiple geofences with a small radius near each other. Or at least run some tests when you need to.
As a rule of thumb, use geofences to target large regions and Bluetooth beacons for detailed object or place related content. For example, you could set up one geofence for a store, and multiple beacons for products.
While Bluetooth beacons are more precise, there are differences in response for 30 seconds or more depending on device and situation. Especially when triggering out-of-range scenarios, because the device needs to make sure there the bluetooth signal is gone and that it’s no temporary lag. You can configure the range (signal strength) and polling interval of a beacon with the manufacturer’s app. The higher the interval, the faster the response, but the more battery power it will take.
Bluetooth signals are blocked by metal, water and concrete. Since humans are 60% water, you might want to place the beacons at ceiling level for crowded places.