Well, they don’t WL everyone, but the numbers accepted from WL each year can vary widely.
Keep the LOCI brief, but give them meaningful info. Let them know soon that they are your top choice and you will attend if accepted. Update with any pertinent info about awards or developments. Ask your GC to send updated grades. If you don’t need FA, let them know that too. Then send another short email with similar info sometime later in April, to remind them you really want to go there. But do not pine away hoping for a waitlist offer. They have not accepted many from WL in the last few years.