The operative word being, "commercial." I'm not saying these mixes don't exist. I'm just saying, I, as a potential mix diver, would never be taught such mixes in the standard TDI/Cave agency curriculum.
And, yeah,
Sheck was one of a kind. Died too early attempting to set a deep diving record in a Mexican Cenote. I get the desire and "ego boost" of doing things like that, but not at the risk of my life or risking the lives of the rescue divers that have to go in and fetch my body.
I'm crazy, but I'm not
that crazy.