The problem with adding more than one super with foundation, is the fact that it will get worked haphazardously, and depending on the flow some of that foundation may not get worked at all.
Giving the colony one box at a time keeps them focused on a smaller area and they will be more apt to fill it more uniformly and completely.
On a strong colony supers of drawn comb can be installed more than one at a time, and is often suggested for a predicted heavy flow, especially if the hive can't be monitored closely. We do this often, as some of the yards can't be checked on a weekly basis.