well I can tell you this:
I was in on the first "beta" they did, here is how that went:
started Friday ended Sunday night.
each player was only allowed 1 hour and then had to start a new city.
not all game features were allowed.
it was the same city - the map area was set, no options to get other maps.
it had server issues until mid Saturday / or that evening.
given the start and end times plus the un playable state for the first 20-30 hours it was really a 30 hour test when it should have been 72 hours.
and given that you could really only do the same city each time I bet many folks got bored and stopped after a few runs.
how much of a test was that ? I think it was more of a marketing game, give a sample and at then end of each game they were doing adverts to pre order the game.
they had a second round beta that I think was the same as the first one.