The length of your instructional text is almost always inversely proportionate to the usability of your product. Unfortunately, I’ve been saying this for so long that I can’t remember if I stole the idea, modified the idea, or came up with it all on my own. Regardless, I don’t want credit for the idea. I just like it so much that I wanted to share it.
I’m not talking about basic text for explaining business concepts. I’m talking about having to explain to people how your interface works. Whether it’s a VCR, iPod, code, web site, or web application, if the product’s interface needs extensive explanation, there’s probably something wrong.