I used the same chart (from the book) for my "superstar" captain....I'm probably the one who mentioned 21 advancements for a 13-year career, part of which spanned the Dominion War.
What I did (after first creating the basic character, a Starfleet Engineering Officer) was took his career by years (based on my original roleplaying), then used the advancements chart...giving him an extra advancement in a couple of cases (to round out the character concept):
2365-7 USS Mendel/Starfleet Security School (switched to Security Officer in '67)...2 advancements
2367-70 USS Monitor...4 advancements
2370-3 USS Monitor-A (switched to Command Officer in '73)...6 advancements (wartime)
2373-6 USS Ticonderoga...6 advancements (wartime)
2376-8 USS Ticonderoga (post-war)...3 advancements
I ended up pretty much with the character I had conceived with that, so it seems to work well.
Davy Jones
"Frightened? My dear, you are looking at a man who has laughed in the face of death, sneered at doom, and chuckled at catastrophe! I was petrified."
-- The Wizard of Oz