https://www.tvline.com/2113742/breaking-bad-creator-vince-gilligan-meth-inaccuracy/l

Is from the creator's mouth a good enough source

In a 2011 interview with NPR, the AMC show's scientific advisor, organic chemist Donna Nelson, confirmed that creator Vince Gilligan took great pains to remix the process in order to avoid accidentally describing to millions of people how the drug is really made.

"That was actually one of the concerns of a lot of people, but Vince Gilligan has been very clever," Nelson said. "You know, there are multiple ways to make meth. And so although his scenes are very accurate, he will sort of [combine] together parts of different syntheses, so that if you just simply followed the one synthesis as it's presented, you wouldn't come out with methamphetamine."