Like the drunken monkey ROFR process, the UY distribution process is a mystery. I don't think any resort has equally-distributed UY. (Note: OKW comes close.) I also think that DVD likes the December UY because it can play the "Look! If you buy now, you'll get last year's points for free!" game almost all year long, since dues are calendar year and for direct purchases are prorated from date of contract signing without regard to UY.
The most recent assessment of UY distribution is here:
https://dvcnews.com/?view=article&id=4071:use-year-distribution-charts-updated-february-2018. I don't think anyone tracks it anymore, given that DVD can reassign UY when they take contracts back.