Why require two schools at all? We could require only single school to get these people on track quicker. We could even drop the weekend format and run them through the school in one day and have a race the next. Or if we really want to get them on track as fast as possible, we could just abolish the school requirement entirely and put the new racer out there immediately.
In terms of preparing people to in a racing environment, two two-day schools trumps everything. One weekend wonders, on average, are less prepared to be in a racing environment because double schools, as a rule, cannot offer the same amount of track time and instruction as two two-day schools.
In the old days, there was no lack of schools. I believe that a region was required to host a school for each national the region hosted. Things changed when SCCA started accepting professional schools for licensing requirements and dropped the requirement for 1 school = 1 national. Suddenly, regions were no longer required to hold a school plus they weren't even covering the nut on entry fees.