Regardless of the platform, if you bust your hump, do everything you can to outshine your peers (qualify quickly, take on collateral duties, excel in everything you can), and get the evals to back it all up, you will advance quickly. Sit on your ass, screw up constantly, and give people a reason to connect negativity to you in any way and you will sit there at your current rank indefinitely. Most people fall somewhere in between, enlisted and officer alike and advance in rank accordingly. I've only gotten to prototype hold on the enlisted side, but I have seen <2 year second classes (made rank off of this past testing cycle and are still in the training pipeline), 6 year Chiefs, and 17 year First Classes; your guess as to which of them is/were more motivated to excel....