Bashing one's brain with the good stuff will result in a rapid climb in tolerance, which is the result of your Mu receptor system producing less Morphine internally due to the external Opioids you ingest. Simply to conserve nutrients and energy while maintaining a constant concentration of Morphine, homeostasis is the true cause of tolerance and WD.
The greater the amount of Heroin, the more Morphine is produced metabolically. This increased concentration of Morphine is detected which sets off a chain reaction ending with receptor cells being less permeable, or downregulated, to their target. Ideally this would result in the concentration of Morphine remaining constant which is what your body expects. Your body doesn't expect to have the exogenous Morphine source suddenly removed, and so your own production is all you have, which is insufficient now your receptors are downregulated. Leading to the lovely physical effects of WD. Upregulation is the inverse of this process in order to return to a physiological baseline. It is analogous to Type 2 Diabetes and its relationship to Glucose and Insulin.
Ingesting the massively variable Diamorphine concentration in street Heroin results in your body constantly trying to correct for your being away from baseline, it makes less sense for your body to induce permanent changes in receptor sensitivity - less tolerance climb, reduced WD intensity and duration.
Ingesting a consistent dose of Diamorphine with frequency leads to rapid changes in receptor permeability - rapid tolerance climb, with longer taken to reverse the changes making the WD period longer.
Your body desperately hates your drug choices, and will do all it can to account for any change in either direction.
