@Alexander, multiple time counts are needed for people living within certain places. A way to measure time locally to keep track of the day, for example. The universe doesn't have a universal reference frame, so we have to create one that's useful to us.
I believe we should abolish timezones, and use the Prime-Meridian (a standard meridian agreed on by most of the world) as a reference, and measure the angle of this meridian to the sun, with 180° being (approximately) solar noon, and 0° being when the meridian is facing the opposite direction of the Sun. Using this notation, 1 degree would be about 4 minutes, and more precise time can be represented with arcminutes (1/60 a degree, or 4 seconds) and arcseconds (1/60 an arcminute, or 1/15 a second).
That said, that would be an ideal system and would require calibrating systems to the prime-meridian, instead of just using the built-in timestamps computer have.
For convenience, using GMT time (or what James is calling AST) should be fine, in my honest opinion. For non-Earth localities, using a degree system might not be such a bad idea. The only other frame of reference I think we can use would be out position within the galaxy, but that's too large to be useful to humans (which is for whom Asgardia exists).
In my opinion though, the adopted calendar is kinda silly. It doesn't achieve anything beyond keeping a whole number of weeks in each month. Weeks aren't even an important enough concept to care if they spill into multiple months. I'm expecting drastic calendar drift to occur with the extra 13th month.