What are some of the many things that you have seen one person be really good at at the same time?
After edit: thanks for the kind reply, but I kind of thought from your original comment (parent to this comment) that you had a more recent example than Da Vinci in mind. What living persons are there who are conspicuously really good at many things?
http://stuff.mit.edu/afs/athena.mit.edu/course/6/6.055/readi...
So my main point is: don't assume from the beginning that you can't do many things well, or it will be a self-fulfilling prophecy.
But if you work on Skills A,B and C for a week and another dude works on Skill A for a week there's no guarantee that you're going to be worse than him. Depends on smarts, I guess.
I guess it's academic but inexplicably interesting to me.
That being said, Scott Adams' career advice[1] seems pretty solid. In short, it is usually just as useful to be competent at three different things as to be extremely good at one thing.
[1] http://dilbertblog.typepad.com/the_dilbert_blog/2007/07/care...
http://moreintelligentlife.com/content/edward-carr/last-days...