My high school operated on a 2-day schedule system. Day 1s were on odd dates, and day 2s were on even dates. On a day 1, classes were in the order A-B-C-D, and on day 2s, classes were in the order B-A-D-C. It was just annoying enough to warrant me creating a schedule program that answered the question of what class you have with the click of a button on your phone.
I used the iPhone Shortcuts app. When you clicked the button on your home screen to run the shortcut, it would quickly display which class you had next, and how long until it starts. If you ran the program while already in a class, it would display how long it would be until the class ended.
I created a website for it, and created working versions for 20 high schools in Ottawa. It never ended up taking off beyond my school, but it was fun to make and the people around me seemed to appreciate it.