I understand your point and it makes since in theory.
However, common since can't be applied in all situations.
I'm 100% sure that the gw researchers took the dosing into account when they ran their models and presented their data to their superiors.
I'm sure the people in charge of distributing research funding took into account the dosing when they pulled funding for a drug the showed positive benefits.
The people who develop these drugs are brilliant and graduate at the top of their class. They know much more than we ever will about how these drugs will affect the body.
Pharmaceutical companies do not pull funding for a drug unless they have a very good reason, especially when the drug shows promise.