Just pondering.....

If the 8992 messaging system is based on the "one time pad", it needs to be frequently updated. I'm guessing once a day, although it could me more (or less) often.
Does anyone have any idea ?

Since large numbers of ships, planes and land based stations worldwide are involved, we must assume that this is done via encrypted satellite communication, "dark web" internet or both.
Does anyone have any idea ?

Although digital transmissions have been observed on 8992 et all, I do not believe that this is how the code is distributed.
I know from personal experience how slow digital communication on shortwave is and how error prone.

They must have a system by which they can control who receives this information. Unless they're confident about their coding or that it does not matter.

Although I realize how time consuming this would be, has anyone ever done an analysis ? In other words how many messages each day, the length and whatever else seems important ?
Does there appear to be a pattern ?

To the casual listener like myself, it seems quite random.