Came looking for this thread because I have a live example! I don't have ADHD, not even self-diagnosed, but I've got executive dysfunction in spades. This is what it looks like:
I'm going to an event this weekend. I paid for my ticket and booked a hotel six weeks ago. In that six weeks, I have not prepared a single thing. I've thought a lot about what to wear on each of the days and what I'll need to take.
I have not prepared anything, much less packed. I'll be wearing whatever doesn't need washing: my planned outfits are all in the wash 😬 I haven't emptied my weekend bag from its last use - months ago - and have just placed a supermarket order to the hotel, to cover off the essentials I'll probably forget or can't locate right now.
I may well miss my train. I booked the latest possible, so I'll have some time in the morning but, as you can see, I need to compress six weeks of prep into three or four hours.
I've been like this all my life - and, yes, I have missed international flights, crucial exams, interviews and surgeries. I am genuinely great at planning. In between planning and enactment, some necessary link falls into a bottomless void and I'm left with plans, panic and failure.
Very, very occasionally, like once a year or less, I do things at the right pace in the right order. Then I marvel at how nice it is! How calm! This must be how people do things, I think; I should do this all the time! The next thing comes and the magical link is in the void.