Are you familiar with the principle of delaying decisions to the last responsible moment (AKA defer commitment)? The idea is to not make a constraining decision until the last possible moment so that information can be gathered up to that point - making a decision early on may seem, to a PMO adherent, like a prudent course, when in fact it is the opposite of what one wants to do.
I've seen, in many cases, where everything should be laid out in detail before a certain amount of work begins. These decisions are made based on perfunctory designs or shallow analysis - not good. When should these decisions be made? Later - when needed.