This ability triggers only twice each turn. As far as play patterns go, Nadu, Winged Wisdom is not a great choice for casual Commander
Yes, one of them will end up in the graveyard, but that shouldnt be a problem in black
For example, if you control both Azusa and Exploration (an enchantment with "You may play an additional land on each of your turns"), you'll be able to play four lands during each of your turns
When Lazav clones Atraxa, Grand Unifier for a turn you dont get the ETB, but you are swinging with a 7/7 lifelinker or youre sitting back with threat of activation on defense
Perhaps after Vivi bites the dust on November 10, Naya Yuna in Standard will prove to be a strong metagame choice
Kaseto hits me right in the feels because Kamigawa, home of the Orochi snakefolk, was the current block when I got back into Magic during college