There is ZERO correlation between what one academy decides regarding their applicants versus what another academy decides. It's not as if somebody at USAFA is going to make a phone call to USNA and say, "Hey, have you seen this one candidate? We are inviting him to our summer seminar. You should do the same!" Nobody at USNA would even know that a candidate is attending another academy's seminar - nor even care, for that matter.
You have to remember, there is no shortage of qualified candidates. About the only time an academy might care about a particular candidate's relationship with one of the other academy's is if the candidate was a highly recruited athlete. USNA would not want to lose a potential star running back to USAFA or USMA if that candidate was applying to all three academies. Yet, seldom do recruited athletes attend summer seminars.