Recently, I was in a hotel and noticed this sign in the shower. That’s right, the front desk finally got tired of explaining to guests how to turn on the shower. Their solution: make signs and put them in all 350 hotel showers! Did the designers do any user testing? Did they have the curse of knowledge and lose sight of the fact that most people have an already existing mental model for how “all” showers are turned on? I don’t know, but I think this makes for a great example of what can happen when your new (and better) design is radically different from the normal paradigm (say, for how showers work). Once you know how it works, it is no problem, but that’s not good enough for this scenario.
In the world of Web design, you may create a really cool new way to do something, but have you considered whether or not it runs counter to a user-accepted norm (e.g., what something is called, or where you have it on the screen). Have you asked yourself whether or not it is worth the potential user frustration. I’ve been there myself: “Once ‘they’ do it once, they’ll understand it.” But, unlike a shower, which people are pretty much going to figure out even if they have to call the front desk, web users might not be so persistent. One shot may be all we’ve got.