One thing to keep in mind…and I don’t “know” this…but I have heard it alluded to by my D who did some admin work for her teacher in UG.
At big schools with big depts, I would guess they have to get a critical mass together to listen to the pre-screens. It seemed at both my D’s school that everyone was extremely busy. Having worked in large institutions myself, I would guess that there are a few dates (or maybe one) to listen to pre-screens set up by the head of the music dept. My D mentioned that her teacher would complain about it…as she was always busy and pre-screens and auditions took a lot of time.
I imagine the pre-screens being collected and then teachers having a date or two to listen. And then off the results go to administration to hit a major traffic jam that takes maybe…mmmm…a week or two (or if you’re lucky they get to admin the week before winter break so…you aint hearing nothing until January!). Then admin will start sending out emails…and inevitably miss your kids…well you know how it goes… I think Dec until mid Jan are the most common times to hear back.
And, yes, smaller depts can probably get this done more quickly and efficiently.