. . . are very costly, actually. More readers, listeners and viewers are lost during the preamble---or introduction or preface or forward or whatever---than at any other point. In printed matter, of course, you can just skip to Chapter 1. You'll feel guilty for the whole rest of the read, but you can do it. If you're listening to or watching something, though, all you can do is sit through the preamble or do something else till it's over. The author or presenter thinks that they're giving you indispensible "back story" or whatever, but what they're really doing is allowing your mind to wander and destroying the impact or significance of whatever you were waiting to hear. More often than not, instead of preparing their audience, they lose their audience to one degree or another. I'm just sayin' . . .