It doesn't necessarily work that way. There's an old story about a young man who goes to a famous master, and asks how long it would take to learn the master's system. The master answers "10 years." The young man is disappointed, but not deterred, and asks "what if I train twice as hard and twice as long each day?" and the master answers "20 years."
While some aspects of training depend on the style, generally, the time taken to reach shodan is recognition of the time it takes to internalize key elements of the system. Sometimes there are a very intense programs that are quicker, like the
Yoshinkan Aikido Senshusei Course -- but they are very intense and demanding programs.
Note, however, that hard and dedicated training will let you develop skill more rapidly.