I think it depends on organizational depth. I spent about 3 seasons in the minors (one year split between AA and AAA, and the last two in AAA), and the fact that I was stuck behind multiple highly rated outfielders definitely factored into that.
Eventually I was traded from the Padres to Tampa, who then gave me a shot at the majors, and then promptly traded to Detroit (given more at bats so I'm not really mad). I think if you spend a year in college, or tell your agent that you're not happy in the minors, or want a trade, then I think it may help speed up the process. With that said, you're not likely to get called up in the first two years unless your organization has crappy depth at a position (maybe someone out there has had a different experience who can chime in?)
Side note: Who else hates the music in this game? That song by Nombe drives me nuts.