I think I can get a second monopoly in maybe 60% of my games, peacefully. But why should I spend my spare time in hunting another monopoly, if I didn't know which one it will be or maybe not even be able to get another? Hexxon is only really helpful, if you go warmongering. If I play this path, (rarely but in the last time a bit more often) Iam sure that I will be able to get more monopoly choices by conquests early enough. At the point in the game, when corporations are unlocked, Iam powerful enough to not care about any military benefit from Hexxon Refinery and instead pick more useful corporations like Centaurs with science and production boost or civilized jewelers which helps to keep me in permanent golden age. Hexxon is in any way a useless corporation, for me beaten even by the far underrated Twokay Food.