I've heard a lot of mixed stories about people adding additional enzymes (Beano, GasX, etc) to their beers to drop the final gravity down very (sometimes undesirably) low. I've also hear mixed ideas on when it should be added.
As per a comment in a previous question of mine, there's been experience with adding it at kegging to assist with dropping the FG after the fact in the case of a botched attenuation, with the consequence of having to lengthen the aging to allow the enzyme to convert all the sugars it possibly can. I've also heard that people may add it during the mash (supposedly common in distillation). If it were added during the mash, would the enzymes denature in the boil, negating the need to lengthen the aging? Would it have enough time during a 60/90 minute mash and the lautering to have any significance?
Are there any other times/methods to adding enzymes or controlling their conversion to assist with dropping the FG in high gravity beers?