I would also be surprised if Shanti went through all the trouble of keeping several copies of selected parent plants spread over countries and continents (as he stated before), only to produce seeds the same way that the Spanish do.
Or he is lying but I doubt that because the results are too excellent and too many people vouch for him and his seeds.
It has been my impression to this point that we are dealing with clones of parent stock that has been kept alive and well over decades. Seeds were made using clones of those original parents (as Patrick described) and the original parents were just re-grown from clone if they lost vigor through the years or simply were lost to raids or disasters or whatever (which is why Shanti says he keeps clones of the original parents spread over different countries/continents).
Would really surprise me if this wasn't the case but I might just have understood it wrong.
Also it was my understanding that one of the main differences between MRN seeds and others is exactly this method of keeping parents alive over decades, while other "breeders", for example Serious Seeds, failed to do the same and lost this or that parent of their AK47 and then tried to replace it with a Chronic parent and later an AK47 F2,F3,F4 etc. parent. This resulted in alleles being lost over the years and the current versions of such strains being a shadow of their former self.
Another indicator why I believe this is the method MRN uses is that you supposedly find a certain range of variety in each pack (which is also one of the reasons they sell in packs of 15 or more, which no one else does).
From what I heard all but the oldest strains (like Shit) will have quite a bit of variety in phenotypic expressions. I assumed that strains like Shit have lesser variety because they were quite inbred already at the point of their creation (afaik Shit is a Skunk#1 X Skunk#1 and Skunk#1, I assume, was quite inbred already by the time Shanti backcrossed it to itself and renamed it Shit).
So I would call Shark Shock a "heavily worked" line, due to its age. But I would assume that you still get quite a bit of variety in a pack of 15.
I have a bunch of Mango Haze IBL seeds, which were marked as IBL by Shanti and sold in the christmas hampers packs. I assume there will be less variety in these than in my regular Mango Haze pack. But I expect deviations from the Mango Haze IBL to be rather small, as Mango Haze itself is a well worked line that has a rather small pool of variety already (or so I assume). After all, people growing Mango Haze, want Mango Haze and not Super Silver Haze expressions. If there still was large phenotypic variation in each Mango Haze pack, I would assume people would sometimes wind up with Super Silver Haze instead of Mango Haze and I doubt both strains would have such a stellar reputation in that case.