No user testing? and you think its not going to bite you in the backside?
You need a first class idiot! You know make something idiot proof and along comes an idiot that proves you wrong.
My sister a hematologist wrote some protocols re using a new ( then ) all singing all dancing machine in blood labs. They had the time so managed to get some idiot ( low skilled person ) to try it. They failed! After a discussion with the failing user the protocols were rewritten. They then became more user friendly.
This seems to be a form of testing that is rarely done in practice, too tight a deadline methinks.