When it comes to pre-assembled furniture, I always read the manual. There's so many weird parts that look alike, but really aren't.
As for video games; it more fun to try it first, and then read the manual. I did read the GT4 manual first though (I was waiting for a pizza at the pizzeria a few doors down), although it was next to meaningless in content, it was whetting my appetite to the point of drooling.
Cars: A little later after owning it, and I always learn something. The Corolla's got a section showing you how to replace and change many things on the car, so I've learned a lot from the owner's manual. I've done more work/maintenance to it on my own than any car I've owned before.
As for my industry; I can tell you about 1 in 100 actually read the darn thing. These are mostly people who have PhDs and other university degrees, and yet they can't be bothered to read one damn book every 36 months pertaining to their new $50,000 automobile. So when one of them actually makes reference to it, I want to hug them...you don't know how many trival problems can be remedied by just using the index!