Honestly, I think this should be an option every year, especially for middle schools and small schools. The lower grade level on the PML are a joke. You might find one piece that fits your band, but good luck finding another, especially if it has to be a different composer/arranger that the rest of your program. There is so much other good stuff that is not on the PML it makes sense to let band have a broader choice on their selections. And, don't give me that "you can appeal to perform a piece that is not on the PML". Yes, but why should we need to appeal to a committee to be able to select music that our students are capable of being successful on while still learning (don't forget, that is the ultimate goal). I know the argument that some directors are going to abuse the system and choose "inappropriate music" but I doubt any director is going to be picking pop tunes or movie soundtracks for their UIL performance, though let's admit that kids would probably work harder to play a piece they are familiar with that some generic band piece that (frankly) sound like every other piece out there.
My groups didn't go to UIL. With our hybrid system, every other day block schedule, and every other other day student groupings, we felt that seeing them 1-2 times a week would be working against us (yes, you read that correctly. For most of the year we saw a group of student 1-2 a week and that was if they we in person. 2/3 of our band kids decided to stay remote). So, this year we just played fun stuff. They still learned about good tone quality and tuning, balance and blend (if in person), and all the other good stuff (style, dynamics, rhythmic accuracy, etc) all without the specter of UIL hanging over their head, and had a better time doing it. Makes me wonder what the point of UIL really is, but that is a different discussion. My point is learning is learning no matter what music is being performed. A superior/excellent/average/below average/poor performance can happen no matter what music is being performed. Standards are standards. What is used to demonstrate those standards shouldn't matter. Lot's of things have evolved over the past year; maybe it is time for UIL do do the same.