It's not impossible that the routes and times one flies is a consideration (direct or indirect) for granting/retaining 360 (as a means of limiting the number of 360s coming through hubs in a given block of time, since the main benefits over DM are in things like ground handling and priority access to the SkyClub). That would seem to account for a lot of observations about how random the invites can be (e.g. $60k in ATL getting an invite over $70k in Florida). If they are doing that, then flying a similar pattern as a 5MM who's retired to PBI or RSW might not count for much.