I don't think it matters to the overall design what the routing progression is as far as par is concerned. Of course you wouldn't want the extreme with all par 3s 4s and 5s lumped together. But in genereal, as far as where par 5s come into the progression, there are so many permutations that work, I wouldn't look for any general rule of thumb since the grounds for the golf are so different from course to course.
I agree with Neil, it all depends on what the ground gives. Of course you can take some of the modern architects and force whatever you want--initial cost and maintenance expense over time makes this seem unreasonable. Try not to look for formulas, Mike; many of the best courses go their own way.
One interesting routing progression in terms of par can be found at the Old Course at The Homestead. There are 3 par 3s, 3 par 4s and 3 par 5s on each nine. The way it is today isn't the way Flynn redesigned the Ross holes but rather a result of Reese Jones's work in 1994.
Front 9: 5-3-5-5-3-4-4-4-3 No par 4s till the 6th hole
Back 9: 4-3-5-5-4-5-3-4-3
Both the Cascades and the Old Course finish with a par 3. The Jones par 3 does not fit in to the routing but this was subordinated to the needs of a driving range.
Merion East's two par 5s are the 2nd and 4th hole, that isn't a problem at all.
By the way, for Rolling Green the par 5s are 7,9 and 17