How fast?

As everyone will know, the school is undergoing construction work. What some people wont know is, nine weeks ago a school in a town called "Toll Bar" was flooded and the school today isn't fit for education. However the pupils of that school now learn in a new school built over the nine weeks the other school has been drying off. Now what I don't understand is, it takes those builders to build a whole primary in nine weeks, yet all our builders have managed to accomplish is gas us all, knock down two parts of the school and then set up two huge metal frames with a ridiculously high crane in about nine months. Our builders must really be crap.