That's interesting. I read your comment in my head while counting and seemed able to keep up, but something more complex might be hard, such as reading out loud.

On another tangent, I've been trying Ritalin after speaking to a doctor. The first thing I noticed when I took it was that it became very difficult to hold multiple trains of thought at the same time. My typical routine (coping mechanism) was to work and have YouTube playing and a little attention on each, because this stopped me getting bored. But it wasn't long before I realised I simply could not hear the videos. It was a strange feeling but nice. A little similar to what you describe in how abilities vary.