H is for Thursday

Ooof, I feel the stench of desperation as I struggle with this post! I've run out of steam and inspiration, but tomorrow looms ahead and I must write about H.
And just like lightning, I realize that in most abbreviations, the day Thursday is abbreviated as H! Joyous Day, I've got my post!
Why is Thursday abbreviated as H? Well, as I google it I see that, in fact, no one abbreviates it as H. They use R. I could SWEAR that when I was in college, it was H. Classes were either MWF (Monday, Wednesday, Friday) or TH (Tuesday, Thursday). Now I need to poll the Internet. Am I crazy? Am I making up the H abbreviation of Thursday because of a blog post?

A synesthete alphabet, but not mine

And now for a twisty little rabbit trail: it's possible that I confused the letters because I have synesthesia, and when letters have the same color, I tend to confuse them. However, it's unlikely that I confused H for R, because H and R are completely different colors. I confuse R with A and K because they are all red. H is brown. If you're a synesthete, you know what I'm talking about...