What Will It Cost?
Once we have determined what must be done at a given site we can then turn our attention to the all important question of how much we can expect to pay. The accuracy of this estimate has an enormous impact on the entire network strategy and must be based on exhaustive (and accurate) quantity calculations.
Another, related question, is how much more will it cost each year I put it off? This ties in with the concept of performance modeling and is a topic unto itself. It is a very important topic though as it has as much of an impact on estimated cost as quantity measurement.