'Way back in the day...'
When nationals were just nationals, there WAS a rotation scheme wherein, each year a different event was held the first day(s), and it's correlating Team, and junior events were held in the same relative days as the first event had the year before; likewise the second, and third events, so that there was a rotation and perhaps even predictibility...
HOWEVER, then, there were MANY less events (i.e. women's sabre, and epee and ALL veteran's events were not official events, just exhibition, and there was only Open, and Junior categories, and no junior team): since we now have official events for males & females in ALL 3 weapons, in 12 age/skill categories, as well as 3 team categories, well that adds up
90 count them
90 events!!! (feel free to chack my math!) - compared to 16 - 20 or so, that were once held!
Now don't get me wrong! I am not saying that there shouldn't have been changes, etc, just that it's a much more complicated problem than it appears, and that it was deemed more important to introduce the stratification that to worry about whether some people might/might not be able to fence in all the events they prefered.
They bottom line is that, if you are an 'up and coming' cadet, or even a junior, and happen to fence foil and epee pretty well, it can be quite possible (at least in some of the non-eastern sections) to qualify for 8 events - (heaven help you, and your parents' checkbook if you want to fence team events!); likewise for experienced veterans, (who are (I beleive) even more likely to fence 2 or more weapons) it can be pretty easy to qualify for 5, 6, or even 7 events...there's just no way to ensure that eveeryone is going to be able to be in every event they might want to fence.
I WILL say that the one big thing that seems to play a 'spoiling role' is whether, or not the Div 1 (a.k.a. the 'real nationals') are held in April, or in July... that is a function of when World Championships are which is something that changes significantly from year to year, and really prevents them from establishing any sort of consistent roatotation at US Summer Nationals, which would still be difficult, in any case.
Additionally, events vary widely in size, based in participation, and location...which doesn't make things any easier. So there's always going to be a certain 'wait and see' factor to this.
I will take this opportunity to remind everyone that Qualification rules for most summer national events have changed this year, so you should go to the USFA website (it's not quite where you might expect to find it) -
http://www.usfencing.org/Documents/R.../QualPaths.asp
OR, you can check the Athlete Programs Handbook:
http://www.usfencing.org/Forms/AthBk2003.pdf (Yes, I know it's not a form...)
And take a good look at them - don't rely on your coaches, or your division's officers to have learned this: many WILL, but many will NOT!