You all make it seem so logical, and so it is important to start with objectives in mind and know the constraints that limit you...BUT once you start to implement you plan.... throw in the possibility that having bought components A, B and C in that order so that A matches B and C matches A and B, what happens when you audition component D and it sounds not so good with A and B, but oh so much better if you switch out A and B for A' and B', gear you had never considered before? Things like this happen as a result of learning by doing recursively rather than simultaneously (which is impossible anyway), and the market doesn't that work that way. This is what some people wrongly call upgrade fever. (Ask Phil Lamm to explain the difference bewteen problems that can be solved recursively vs. simultanously)
I think that this is wrongly named. The majority of people who upgrade are doing it as a result of learning more about their own preferences for sound and how various technologies, brands and models fit together with that. I think that is also what makes the process/journey so much fun, because we are always finding out new things, often randomly, and we have to figure out how to fit this all together in our heads, our hearts, our checkbooks, our listening rooms. It isn't easy. And then get the wives to agree....
I say be preapred for surprises. Don't fear them, enjoy them, just as you learn to love a new composer or the solution to a set of higher-order differential equations!