In regards to being able to complete work faster after the other kids have already left for recess, is it not possible they are a distraction? General ADHD distractability or sensory issues that cause trouble with filtering make an empty room much more conducive to getting work done. I honestly think this is true for anyone, but especially for kids with issues remaining on task and focused. Your child may not be able to identify this and therefore "doesn't know" why it is easier to get the work done in those few minutes.
