<p>Everyone has already given good answers to Platero’s question. Taking three (or even <em>gasp!</em> four) years allows you to build more friendships, get to know more of the faculty, essentially get a degree in an additional field or fields if you want, etc. etc. </p>
<p>My reason is that Caltech probably has the highest concentration of absurdly smart people on earth. It’s certainly one of the top five locations in that regard. Why you would want to get out of here as fast as you can – especially given that you are applying to be here – is hard to understand. If the reason is that college, for you, is a race to get a required number of units and a prestigious degree and then get to the “real part”, then Caltech is probably a bad place for that. For the people who do best here, Caltech is the “real part”.</p>
<p>I hope that makes some sense, but please poke me more if it doesn’t.</p>