I like that you use letters to make it clear which time is being discussed, cool idea and important - the problem with organising cross timezone isn't so much the complication of organising across timezone (you can look up a conversion online instantly and easily), it's more the ambiguity about which time any particular time being mentioned is.

I didn't originally create a new week for my system, but knowing which day a meeting is on is important too for meetings that are a long away apart. That's why I created nullday, unday, duoday, triday, quadday, pentday, hexday, heptday, and nonday.