Sometimes the modeling process in 3d studio is exploritory, in that the student is still designing while making the model. It is only once the design is more finished that they move to more traditional drawings.

But, if you already know exactly what the building is going to look like, then yes it is usually easier to import the cad into 3d (assuming you have a somewhat orthagonal building)

If you are designing, you need to work in 3D - plans and sections come after (or during).
If you are just rendering someone else's design then you need to have the plans/sections to import into Max.

Two completely different things.

i've been put down by a guy in this forum not long ago, because hes pro BIM, where everything is preety much....well integrated, but i feel that the exploratory part in 3d is as its ever been since ..i dont know paper and pencil......in that sense, i've found sketchup super-duper cool, and depending on the environmet and the purpose, i always think of technikal drawings later or after the exploration is done.......and then i get photo-real, but i find it innevitable when ur in photo-real mode to keep exploring.......so i gues in some sense the BIM dude is somewhat right..... :op

Does anyone use 3d studio in the design phase as it is very time consuming? I can imagine that it only used as a presentation tool once you have al the measurement which can be imported in 3ds.

It just depends on what software you use. I do not know of any firms that use Max only, but no reason it can't. FormZ is the more common platform for designing with, and is significantly faster than trying to build models (although I think you still should). There is no way you can really explore the spatial qualities of a building in 2D, regardless of how good you are with paper and pencil.

That is, unless you are simply making boxes.