For region monitoring (typically used for the "notification" case) the limit of "fences" is indeed 20...it gets into a bit more detail about "what's a fence" [e

For region monitoring (typically used for the "notification" case) the limit of "fences" is indeed 20...it gets into a bit more detail about "what's a fence" [edit: most of the time you can assume one monitored beacon == one fence]. But for "ranging" meaning "what beacons with this UUID are around me", the system gives you a report of visible beacons every second with no (defined) upper limit.