Honestly, if your ADC does really well, Yorick's late game job becomes "protect the ADC."
IE - Team fight starts, you ult your ADC and peel for him, you now have 2 ADCs on the map due to your ult, and he'll either die because of the enemy team, and then get a free temp GA, which most people dont expect because Yorick only ever ults him self, or your have 2 ADCs till your ult wears off because you managed to peel well for your ADC.
But if your ADC is shit, you're pretty much a win the lane, lose the game champion.