Rapid travel is a highly valued commodity in any setting. Instantaneous travel is invaluable. The group that controls travel controls populations (see Dune series, books 2-4). Any rival that develops their own circle network is a threat to their gold and their power. They go to the other houses to cash in favors owed to hire trackers, assassins, and entrepreneuring adventurous troublestabbers to find the "trouble", and stab it.
As for PrCs, there are as many as plot allows. During the world wars, how many field agents in the SAS and OSI? How many knights attended aurthur's round table? How many individuals in the Tuskegee airmen? 19th century secret service agents at a given time? How many special forces are there as a percentage of overall soldiers?
As for PrCs, there are as many as plot allows. During the world wars, how many field agents in the SAS and OSI? How many knights attended aurthur's round table? How many individuals in the Tuskegee airmen? 19th century secret service agents at a given time? How many special forces are there as a percentage of overall soldiers?