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I've done it once when my select menu was trolled by a guy last picking top when I was already top... I hate trolls.
I also tried it in a norm after to test how well it could work since the troll fed and harassed the team all game, and the adc would hardly play and kept harassing me for picking yorick support.... no matter how many times I told him "I didn't, I picked top and we were trolled." he still harassed me for picking yorick support...
Anyway, it does work ok. The sustain is great, the harass is awesome, and the slow is weak but enough cc to help (though I would suggest only trying it with an adc with their own cc/escape).
Basically in lane you focus on harassing the enemy adc way from farm. The funny thing is they won't realize they are behind if they are killing your ghouls because they get counted on the cs stat. So if yo do it right they won't even know they are weaker when they go in for a trade and it will get them killed. Also yorick is tanky enough to stand up to a bit of abuse and heal back up so you can linger in front of the adc and zone well (be careful with this though it's a more advanced tactic that most adc's don't know how to play with). Yoricks ult... it's not great. At least with it you can help the adc secure kills and if an assassin does manage to jump on the adc and kill him you can still win the team fight but in lane it's almost useless other than if your adc gets to carried away and dives a turret. (best play I did with that was tanking the turret myself while my adc killed their support, I tanked the turret longer because the adc was chasing and before I died, giving their support a kill I ulted my adc who managed to get the enemy adc down to one shot of health before the turret killed him, then popped back up for the double kill. It was a fun play).
So don't get discouraged by the people who are not willing to theory craft on their own. yorick support has possibility.