Earlier quoted context omitted.
People with ADHD tend to be very fast thinkers -- indeed this is part of the "problem" because while we're having a conversation with someone, we've thought through every consequence of what you just said before you finish your sentence. Because of this, we tend to get to "outside the box" type solutions much more quickly than others because we can effectively execute parallel tasks in our minds and come up with an a…
Are you sure that "hyperfocus" is a symptom of ADHD? I'm a developer, depending on how well rested I am I can go into that zone for 12 hours, sure, but I've always been like that since I was a child and if I want I can focus on subjects that don't bring me pleasure at all, it's all a matter of determination (edit: for me). Observing children at my wife's kindergarten that allegedly have ADHD, it's quite the opposite…
When unmedicated, an adult with ADHD literally cannot focus on a subject that is uninteresting. You try, then OOH SHINY. You can try cutting out distractions, great! You get 5 minutes of work done then you have to pee. Then you notice a magazine on the table. Then 3 hours of this later, you remember that you originally had a task you were trying to complete.
It goes beyond simple procrastination: short term memory is a real issue in general, especially about doing things. It doesn't matter how hard you need to focus, you'll constantly be distracted, and when you get distracted, you forget what you were originally supposed to be doing. Likewise, you may then hyperfocus on something that is interesting to you and end up playing around with an Arduino for 4 hours without realizing it. You know how you have a nagging feeling you were supposed to do something? That's pretty much life for an adult with ADHD. A constant feeling that you're forgetting to do something. But you can't remember what it is.
It's hard to explain the difference between ADHD "hyperfocus" and just being "in the zone"; but I'd have to say it's the in-the-moment perception of how time passes. Most people when they're "in the zone" make a conscious decision to stay there: with ADHD it's almost an accidental thing where you enter a trance and only leave it when your task is done or when someone smacks you across the face.