This thread has a good discussion of bleed order:

http://www.brickboard.com/AWD/?id=606516

When I do mine I bleed one at a time (I forget the order I used).

I remove as much fluid as possible from the resevoir and then top
up with fresh. Then I use the Motive pressure bleeder which makes
the task pretty easy:

http://www.motiveproducts.com/

I bet the tech did all 4 at once to save time. Seems like this
would also require more fluid since new fluid would be flowing
for as long as it takes to do the caliper furthest from the wheel
(so the shorter paths are left open longer then needed). I suspect
a techs time is worth more then the cost of the extra fluid so they
do it as fast as possible.