FWIW, I was glad they opened registration for all the HS Fall dates at the same time. A few reasons:
a) My desired date was at the end of the range ... I could have still canceled my
DVC room reservation w/out penalty if we didn't get tickets. (The earliest event dates were already inside the 30-day window and unable to cancel w/out going into holding.)
b) I figured it increased my chances of getting a booking. All of us hitting the website were limited to one event night; not everyone competing in the process was trying for the same event night.
c) Lastly, I'm guessing combining the nights made it easier on their coders to restrict 'successful booking' to the recent rule: "only one event night per park." If each event registration were conducted on separate dates there may have been one extra lookup to run: "Has member already booked an event for this year at this park?" That may not have phased most commercial programmers ... but Disney's team ... oh, shudder the thought.
While I was frustrated by the many errors encountered (server dropped connection, internal server error, too many concurrent users, session timed out, etc.) ... I wasn't put off by having all HS Fall dates lumped into a single registration marathon.