It is interesting when there are coaches that know the alignments a week before they are announced! I think the long gap in time is for lobbying to take place for certain alignments.
Also, it is difficult to justify the large salaries of the IHSAA commissioner and his minions if the process was done and completed in a weekend. I think Illinois is able to finish the season, determine what 256 teams qualified for the playoffs, classify them by enrollment into 8 classes of 32, and seed all 8 classes in a single weekend!