Originally Posted by Often1

Despite the fact that anecdotally it is not a problem, you should be fanatic about every aspect of booking information.

It only takes one obstinate subcontractor to a contractor to an air carrier, border official or whatever and you are either out of luck or standing around for hours.

Where it can matter a lot is in the US is with expedited border crossing and security checkpoint programs such as Global Entry. As those expand, the need for accuracy becomes critical as machines simply compare coding.