If you ask a device for its location from the dashboard (and assuming it is online) it should update within a couple of minutes and be pretty accurate (usually GPS based).
Otherwise the number of samples can vary a lot depending on what the underlying Android OS wants to do. For example, if it is low on battery it may decide to shutdown the GPS chip, or reduce the sampling frequency a lot.
If the device is actively in use and has a good charge usually the GPS samples will be frequent. As soon as the screen locks from inactivity the sampling rate drops off. These things are all controlled by the Android OS, and it varies between flavours of Android.