Imperial promotion question?

I was just reading Republic Commando and the Storm Troopers were talking about "carreer soldiers" and whatnot. So it got me wondering- how long does it actually take for someone to promote up the ranks in the Imperial military? I'm talking about going from lower ranks like recruits, to higher ranks like captain and colonel...or the highest ranks like admiral and general?

Promoting up through the ranks was typically a decades-long endeavor for most(hence "career soldiers".) For example, it usually took 10-15 years just for most Imperials to promote from Lieutenant to Captain. Nevermind Captain to Commodore to Admiral to Grand Admiral. etc. etc.

...Unless your natural aptitude in tactics/strategy/leadership makes you a distinct prodigy, of course. In those cases you get fast-tracked up the ladder immensely.

*see Thrawn, who went from an Academy cadet to a friggin Grand Admiral in less than 10 years.* Lol.

Pretty sure Tarkin was also fast tracked, but he knew Sidious personally and was favored.

At Galan Yup that was pretty cool in the cartoons, Thrawn was promoted by the emperor himself after some huge victory for the empire.

I think a lot of the old republic brass who stayed loyal to Sidious were also heavily promoted.

Thrawn's victory at Batonn is what prompted Palpatine to promote him to a Grand Admiral.

...Though that battle was more of a mess than Thrawn would've liked, given the sheer number of unwanted/civilian casualties(which were a direct result of Pryce's ineptitude, btw.)