The caution here is two-fold: you won't get a great percentage of completeness without involving users, and you can't always rely on design myths to be true in every context.

Question, question, question. Question business intention. Question user goals. Question your own beliefs about design. It's important to know that you are making design decisions not out-of-hat, but that meet the needs of all aspects of the system within the correct context(s) of use. Which, on its own, is really hard to guess your way to success.

There's no need to add to the collective insanity in the world by designing without this level of attention. Things are bad enough out there. While that kind of drama may play well on stage (I'm looking at you Oedipus), it isn't good in a product or service.