2 and a half days is plenty for each phase. Sure, it sucks that it's only that long per 2 weeks, but there's plenty of reasons for it.
One is that they've said they're going to focus on different aspects in each CBT, as well as gradually allow more content to be accessed (IE: Level cap raising). The short time will give you plenty of time to test the crap out of the game, but not long enough for you to really be fully satisfied, it leaves you wanting more (which is a good thing, for the devs)
Also I hope for problems that delay the beta by about 4-5 hours >.> /petty
I work Friday and wont get to play till about 7:30pm PST *sadface*
Though I definitely wont mind missing the scary, horrible starting area mob of players. That was just horrible when the EU special test went up yesterday....so many people.
My lab is on Fridays 10.00-13.45 - guess I will be a bit late to the party.
I would venture to say that a good part of what they're doing over these tests is load balancing more so than bug fixing. The code is probably modified but mostly what is already being used elsewhere. They're basically stress testing for a few weeks.