In my experience real problems from both are not about the specific day or date or numerology, but about the psychology behind the choice - which inevitably causes problems.
With Friday pushes, someone is inevitably in a rush to get something out despite the risks and ignoring that most folks are going to be checked out and unavailable regardless of what they say (because most people are working M-F). Which is a recipe for disaster. If the company has a shifted schedule or something going on, the same danger could apply on a Monday, but Friday’s are a problem 99% of the time.
With something like ‘the 13th’, it could be someone intentionally picking things that have no obvious rational reason to be a problem but that make some people uneasy and worried for non-rational reasons.
While most of the time that isn’t a problem, sometimes there actually is a problem there, we just haven’t been able to figure it out rationally yet, let alone provide a useful counter measure. And people feeling uneasy, even if they aren’t rationally aware of it causes problems on its own. We tend to go where our mind visualizes we will end up.
After all, it is generally a bad idea to be walking under ladders or scaffolding without a hard hat for instance, and broken mirrors are dangerous. Just not for 7 years, assuming one has a vacuum and cleans it up well enough after.
And if people are uneasy about something, why intentionally aim for it? Why not avoid it? Or at least just ignore it.
Assuming there isn’t some huge pressing benefit to doing the thing that is making people uneasy anyway, which I’m struggling to imagine why it would be important to hit all the numerology ‘bad numbers’ in Apollo’s case for instance.
Lessons were learned, but not the ones expected.