Not to detract from the rest of your post but why would you plan to put yourself on a 12 month upgrade cycle?
I felt a little bad trying to justify upgrading after 4 years, if it's just 12 months, just save your money and wait.
Don't know, ask the people who do it maybe?
My point was that if you must upgrade so often, now that we are no longer in CPU stagnation hell of the 2010's, then spending less more often = better performance for more of the time, while spending roughly the same over the 3, 4, 5 year period.