The answer, surprisingly, is no. While you may think that potential employers will be fascinated by an hour-long epic of every last product of your college career, trust me when I say that they won't be. On average, they'll sit through about of three minutes at the most, and they'll already have decided if they're interested or not in half that time. The rest is a waste of your time, and theirs; the most important thing about your demo reel is maximizing the impact of your reel while effectively utilizing the time provided. Let's go over a few things to keep in mind while preparing your first demo reel.
Know Your Time Constraints.
Often your demo reel will be given to you as an assignment in a class devoted to completing the project in time for graduation; many schools impose time constraints within a certain range. I remember that my demo reel had to be at least a minute and a half long, but no more than two minutes; this is an average range, though some schools will go as high as three minutes. Later, you may be piecing together a new demo reel to meet submission guidelines for a specific employer or call-out, but no matter the reason, you should always check the minimum and maximum lengths of time allowed. This will help you plan your content, and how you will space it.
Use a Soundtrack, and Use it Well.
You may be wary of setting your demo reel to music, but choosing the right soundtrack can make or break a reel; synching your animation clips to a music track can add a needed "punch" that can leave a real impact on viewers. Try to choose something that can be easily edited down to within your reel's time constraints; often tracks without words are better for this, and finding that right "cutoff point" within your allowed time range will probably end up deciding the final length of your reel. Try to use music with a clearly-defined beat, quick-paced and infectious without being jarring; a clear climax of the track can also help you use the music to string entirely unrelated clips of animation into a sequenced story with a beginning, middle, and end.
However, one thing to always remember when choosing music for your demo reel is the issue of copyright infringement. This is a very heated topic lately, as we all know, so I'll pass on the advice that of one of my old animation instructors gave to me:
"For the most part, whatever artist or band you pick for your reel track won't ever see your demo reel. They don't know who you are, and don't really care. Recording companies aren't really going to care much; it's not like you'll be making millions of dollars off that demo reel--well, some of you might, I don't know--and like the artists, they ain't never gonna see your reel or care who you are, especially if you paid for the CD you got the track off. But there's always that off chance, you know? There's always that one person who says "it won't happen to me", and then they get caught out, and get in a whole lot of trouble over nothing. So if you want to take a chance, take a chance. But if you're really worried about it, look at the CD jacket and get the address of the record company, or go to their website. Write 'em or email 'em for permission. Cover all your bases. Odds are they'll say yes, and your behind will be covered."
In my opinion, it's better safe than sorry, and I'd prefer to do everything above-board. But it's up to you to use your own good judgment, in this case. Now let's get back to preparing your demo reel.