It sounds like you're running with the assumption that there is a consistency in the dosage. I admit there would be for cigarettes. Despite different brands off

It sounds like you're running with the assumption that there is a consistency in the dosage. I admit there would be for cigarettes. Despite different brands offering different amounts of tar and nicotine most people stick to a particular brand and smoke a particular amount in a day. However for ecstasy the dosages may well fluctuate wildly. Obviously to start with it isn't habitual so frequency isn't usually consistent. Even with a consistent "every Saturday night" (probably the most common dosage) due to the struggles of supply and demand in a black market you will take different quantities of different stock. I.E. One day you'll have rubbish "Roles Royces" and you'll have 6 of em, another you'll have some nice "Mitsis" and just take 3 and on other days you'll have an insane "Red Tulip" that was incredibly more potent than all the others so you only needed one. Of course the name never really means anything as you can have both good "mitsis" and bad "mitsis". Then there is also the case where the pill is actually cut with something else (pretty common I believe), perhaps a bit of ketamine or god knows. The issue perhaps is that an "ecstasy" in its black market form may be very different from its medical definition making it very difficult to compare like for like.