Often times I come across MEP firms that ask, “Why should we do this in Revit, our process is just fine the way it is?”  To which I ask, “How many projects do you have errors on because you didn’t coordinate routing?”  All of them.  The question isn’t why, but how to use Revit for engineering.  Do you need to model every bell housing, strap brace and bolt?  You don’t, the manufacturer you are specifying already is modeling it.  Raise the intelligence of your employees by having them establish relationships between all the architect’s walls, floors and ceilings by drawing in 3D, you’ll be glad you did.