So, if mash temperature below 153F and if pure o2 and plentiful yeast is pitched, what would cause under or over attenuation? Recipe? What if the recipe is a pilsner? Or a simple IPA? Could too much pure o2 cause problems?
Isn't attenuation really controlled by the recipe and the mash temp? The yeast will do what they will do and assuming you use the same strain repeatedly they should be consistent. Unless you shock the yeast somehow.
My experience with what I would say are under-attenuated batches is more a factor of an excessively high OG with solid attenuation and good final gravity. Along the lines of >1.09 down to <1.015. However, the beers are sweeter than they "should" be to match the commercial examples. To control that, I'm adjusting recipes to bring the OG down a bit so that the beer finishes dryer with the same expected attenuation.
I don't know about over oxygenating. My understanding, which could be wrong, is that it's pretty hard to over oxygenate.