Hello @tobee, your post really resonated with me and I have ADHD without a shadow of a doubt.
I work in quite a stressful finance job that involves investing large sums of money. I find I am crap at everyday admin stuff (e.g., answering emails, writing annual reviews for the people I manage, etc.), but I am excellent when markets are volatile and everyone else is panicking. I go into a calm space and am able to be quite decisive about investment actions because I can ignore the noise, see the opportunities and act on them. I am good in other crises too, for example if someone is injured. Other people take longer to react and sort of flap about, whereas I instinctively know what to do and get on with it.
Like you, I find people talking through lots of hypotheticals really stressful. There's too much to keep track of! It sounds like my DH operates in a similar way to your DSis. When it comes to life decisions, he likes to speculate about the variables involved and talk through (over and over again!) all the different potential outcomes. I hate this. It makes my brain explode. I like to wait until I have the actual data needed to inform our decision making, then go from there. I used to argue with him a lot as a result of our different approaches, but I have learned to bite my tongue and he understands me better too since I got my ADHD diagnosis.
More generally, I find unnecessary complexity extremely frustrating.
For me, these characteristics are a defining feature of my ADHD brain. I agree, they are not spoken about much. I do all the other typical ADHD things - leaving my front door keys in the lock several times a week, forgetting appointments, drinking WAY too much coffee, finishing people's sentences, walking quickly, listening to podcasts at 1.5x speed... however, for me, if I had to pinpoint the things that most characterise my ADHD, they are an intolerance of unncessary complexity/hypotheticals and an ability to act instinctively and decisively, especially in a crisis.
I hope that helps. If you haven't had a formal diagnosis, you should look into it.