the question (and the answer) might sound trivial. People will invest in their best skills and strengths. Most people at least.
As a player, I tend to buy every sorts of skills before seriously investing in one. My favourite D&D class was, of course, the Elf - the one who can quickly become a second rate fighter and a second rate wizard. The general ideia behind this behaviour is that my character will adapt better under different conditions, enhancing my chances of survival. Guess what? It doesn't happen that way.
That's because, as I've learned recently, this adaptation-to-survival works to a certain degree. There comes a time when it's hard to develop specific skills, your true skills, just because you are diversifying so much. Sure, adaptation is good - but it's not a good main skill.
That's why it's good to find out which skills you really want to develop.
(PS: No comments on my first focus day? Come on, people. I need some advice here.)
(PPS: Thanks Patrick for introducing me Polldaddy)
(Image taken from www.wizards.com - no copyright infringement intended. Will take it down if necessary)