Earlier quoted context omitted.
Oh, come on. “It takes me 15 minutes to get to my destination. I should leave 5 minutes earlier than I need to in case there’s traffic or whatever.” Set an alarm for 20 minutes before you need to get there, and leave when it goes off. Done. I will absolutely trivialize it because everyone I’ve ever known that’s like that simply leaves at the time they’re supposed to already be somewhere. Or yes, they get distracted a…
You clearly don't have these issues, and I doubt you care about anyone who does, because your "Oh, come on." response positively reeks of 'that's not my experience, so other people's can't be that different.' It's never just one thing like travel time, it's scores of steps in a routine, which aren't always the same, and can easily be derailed by anything unexpected. You can estimate how long something you do frequent…
There are things we're good at and things we need strategies to mitigate. I may not have ADHD but I have friends and family that do, so I'm familiar enough with it. What steps in a routine are needed to leave the house? Find your keys and wallet? Always put them in the same place. Go to the bathroom and maybe check how you look? Set that timer I talked about 3 minutes earlier. Other people with your condition can handle it; so can you.