I've always believed that the main Dividing Line is between Planners (who think they can solve the whole design on paper) and Builders (who let the design evolve significantly in the field during construction).
In that light, I believe that Builders have the advantage that their design is evolving on an everyday basis during construction. In our case we have anywhere from 3 to 8 sets of experienced eyes out there building the features of the course ... and I think when you have that sort of attention to detail that it's less likely you are going to see the need to make changes soon after the course is finished.
I'm not sure there is ever such a thing as "nailing" a design but I think it's more likely that some designers second-guess themselves too much. I have seen plenty of greens evolve for the better during construction, but I have yet to see one where a client didn't like the first version and the second take turned out better.
As for building in room to expand, it's hard to do nowadays -- in general, if we have left any opportunities on the table to extend a course, the client would prefer that we just go ahead and build those tees while we are at it. I've always prided myself on trying to be efficient with space, because more acres = more money; but the more efficient you are, the less room you've left to expand.