Fair. I wasn't replying to you, your #1 sounds a lot like what I'm saying, though.

  1. I remember hearing the system was only designed for
  XX operational hours but was being run over the
  operational spec.

This is very similar to my "at least" which is very different than "at most". In requirements we wouldn't bound ourselves like that. We wouldn't say our system should run for at most 8 hours. We'd say it should run for at least 8 hours. However, we won't say what happens after 8 hours because we don't test it (it's not a requirement). We may communicate to the operators that the system should be rebooted after some period of time if there's a known or anticipated issue, or we may include a soft boot to reset things. For many of our systems, their operating time is usually under 12 hours (they go on aircraft that don't fly for days at a time, mostly), so we never test anything past about 48 hours anyways. If there's an issue that arises around 96 hours, we'd never know from our testing and only know about if an operator pushed it to that limit and recorded the circumstances properly.