I've had many colleagues go on what is known as a press check: You travel to the printer (which could involve up to eight hours in a car, in the snow, while you're sick) to be there when your book (or catalog) is on the press. Then you check it for color and other errors as each section prints. Somehow I've always been lucky enough to avoid these gruelling trips--possibly because I'm not a designer, but more likely because I rarely work with four-color books. I have gone on a few printer visits, where you get to tour the facility, have a nice lunch, and be on your way. A press check is a whole different beast.
So thank heavens for Liz and Anna at Chronicle Books in San Francisco (whose catalogs I luuurve). They went on a press check and documented it with photos--so we don't have to.