There is also a matter of time. Some people don't get promoted until several years pass. If you look at a particular position or job listing, they say 3 years as a manager, 6 years doing Ruby. Find out the time requirements by reading job postings. This will tell you what is realistic in terms of time in a position. Compare 4 or 5 very similar listings time requirements. There is a little bit of flexibility with this, but not as much as you would think.