Structurally it should be fine. I'm sure that it wouldn't be damaged if sectioned by the lab. Sectioning the bridge should not affect the long term success of the bridge and crowns.
personally, i do not see how the contact areas between the teeth can be correct if it was one piece and was cut into 3. although one way around this is to cut it and "post solder" the contacts. Post-soldering is "patchwork"-- it is weak itself and means the restorations had to go in the oven again, which weakens the restorations..
What is best for you (one splint or a 3 unit bridge and 2 crowns) depends on many factors best left up to the treating dentist.
I personally would not accept this dentistry. Individual crowns are made differently than crowns that are part of a bridge. the fact that your dentistry was toyed with and adjusted after it was finished in my opinion makes it more prone to failure after it is permanently cemented. For example, it's been in the glazing oven at least one extra time, and it was cut after it was completed---this creates the liklihodd of microfracture in the porcelain. these two things weaken the restorations..
Sounds like your dentist has a poor line of communication with his lab, and was willing to give you something other than what was planned. either scenario is disturbing, as is the notion that he is willing to give you a 5 unit bridge cut into 3 pieces and call it brand new dentistry.