Oh sorry, now I see what you meant. Uriah did not name the eastern theater OKW but OB East and created a new command level all for himself above the theaters. Sneaky! Yes, I guess OB Ost would be the appropriate name there.
That would be efficient, and probably make sense for armies that move around a lot, but personally I also tend to give my armies names according to their area of responsibility. Well, maybe that is because I would forget where the Dritte Armee is located, but I'd know where to look for the Westwall Armee...And why also not name the armies by their numbers?
Erste, zweite, dritte, vierte, fünfte, sechste, siebte, achte, neunte, zehnte, elfte, zwölfte, dreizehnte usw?
Now, while I'm taking the time to leave a post, I can't leave again without praising Uriah (again) for this excellent AAR. It began with a high quality and only got better and better. I'll certainly be staying until world domination is achieved.