A common meme you'll see on ADHD in online posts are about how people with it are perfectly calm during emergencies, but then when any inconsequential thing happens such as e.g. breaking a shoelace and they'll just unravel and/or take forever to deal with it.

There might be a correlation, but I doubt causation. I would argue people with ADHD, like myself, tend to end up in situations where extreme pressure and chaos is more common. Thus, we have more exposure than the average person. I imagine it can be a trainable trait in many people.

Yeah, I think this is the key point. I am better at handling chaos because I grew up around chaos (my mom has adhd and so do I) so I am much better at handling things falling apart.