Last year DD received competitive noms to USAFA and USNA from our Congressman, who uses the principal + 9 competitive system. She also received noms to USAFA, USMA, and USNA from Senator Harris in CA. We do not know which method the Senator used, but I do not believe that DD was a principal for any of the those nominations, although I suppose it is possible. She had an LOA to USCGA, but not to USAFA, USMA, or USNA, although she did receive an LOE from USMA.
Fast forward to spring of 2019. Our Congressman held a meet and greet for the 9 appointees from our district. There were 3 to USAFA, 3 to USMA, and 3 to USNA. Of those, 1 was his principal to USMA AND 1 was his principal to USNA. The principal for USAFA dropped out for unknown reasons; not 3Q, chose a different school, or some other scenario. In any event, of the 9 candidates in our district that received appointments, only 2 were principal nominees. I believe that 2 of the others received LOAs as recruited athletes. That means that 5 of the 9 were not principal nominees, nor did they have LOAs. So the majority of the appointments issued went to candidates who were simply competitive nominees.
Moreover, some percentage of the 9 may have received multiple appointment offers, since most, if not all, of them had multiple nominations from the Congressman and may have also received nominations from other sources as well. I know that at least one of them, my DD, received appointment offers from USAFA, USMA, USNA, as well as one from USCGA. I don't know to what nomination source her appointments were charged, or the charged sources for the other 8 appointees in our district, although presumably the 2 principals were charged to the Congressman.
The point of all this, is that the central issue is not what nomination method the MOC uses, or whether the MOC has open slots available at one, or all, of the SAs. Based on a review of our district's appointment history in recent years, it is clear to me that our Congressman almost certainly did not have open slots for all of those appointments last year. So it really doesn't matter if you are one of 9 competitive candidates, or a principal nominee. If you are 3Q with a nom, and if the particular SA wants you, you will receive an appointment.
Control what is in your grasp and ignore everything else