[sirdarksol]

I'm sorry. I had to read this post twice to make sure that I understood the concept right. Actually, I'm still not sure that I got it right.
What I'm getting is that you're bothered because it will take you "several years" to master something as complex as karate. Is this correct?
If so, God forbid you ever take up traditional samurai or ninja training.
In this case, we'll take "several years" to mean five years. I'm basing this on my dojo. Others will be different. And as Chayudo said, each student will progress differently. (A parable about an overeager student questioning his master on how long mastery would take comes to mind at this point, too)
During this time, you will not just be learning new moves, you will be continuously improving them. You will be learning many katas, which help you flow from one maneuver into another. You will be training with weapons, which also help your unarmed abilities (punches are so much easier since I picked up bo).

Honestly, I don't think too much of any art that only takes a few months to a year to "master." That's not enough time to truly learn anything. By the end of that time, you're only beginning to pick up the nuances of the moves you are learning.
There's something to be said for being well-rounded, but dabbling in a bunch of different arts can only take you so far. I believe that to really learn, you've got to stick with something, even while working on different arts.