This ranks so far down the list of problems with society that it's not even worth mentioning. But every day of the week should start with a different letter so they are easier to abbreviate! Having two "T-days" is just fucking nuts to me. I'm ok with the weekend days both starting with the same letter because that can just be a signifier that it's the weekend. But ideally? Every day gets it's own letter and you can just say "something happens T-day" instead of "something happens Tues".