I don’t know vyvanse xr method of action off the top of my head…
But for opioids the difference in in enzymatic breakdown is already problematic.
Even for non XR, some people just burn thru it at different rates.
Personally I don’t have enough of a couple of the L enzymes and that means most opioids barely do anything to me. Some people have too much and will burn thru a Vicodin in half as much time, leaving them unmedicated for half the time.
There’s just too much human variation for a one sized fits all approach.