All these things are great, but I for one will never finish all of them in one map, maybe 50%. Reaching "MAXED" on every Army Camp, Mine, Dig Site & Hospital is simply unobtainable because it increases amount of time on a map Drastically.
Is it possible to get these things easier to obtain to help balance things? Maps are long enough to finish one, at least my goal is to kill all as fast as I can and get to next map. Maybe some people do not play that way?
As you point out, the goal is to beat the level, not to upgrade any buildings to max.
Each building has a different max level, and some are reached earlier than others. I've got MAXED a few times, but I rarely ever need to max out buildings before finishing. That is partly due to the fact that I get bored of waiting, and use about 10 powers to finish of the level.