Reality changes and the brain works at keeping that reality organized so we humans can develop a coping strategy. ADHD creates significant problems with handling change. Rates of Change make a big difference.
The single most visited post in all of the almost 7 years that I've posted medical updates at CorePsych Blog is this posting on Vyvanse Water Titration - slowly is best with any stimulant as outlined in this video.
Common Sense: Working memory imbalances don't interfere with working memory in every circumstance, they only gum up the works, like molasses in January.
One of the main reasons some of the stimulant meds don't work effectively is that they don't cover every essential neurotransmitter system necessary for efficient pre-frontal cortical communication.