Phone your local terorist group and try to get Osama to join you at a local bar next week to share some brewskys, and you'll have as much chance for success as you would if you phoned a top restaurant and asked what days next week the top chef will be working. Does anyone know how to find this out? (About the top chef, not Osama.) If ever I went to Per Se I'd sure like Mr Keller to be there, and similarly for Ducasse.
Does it matter? The restaurants claim, vociferously and unanimously, that it does not. The sous-chefs are trained so well, they say, that they work as well with the top guy absent. But I wonder if this is true. Imagine that you are a line chef and it's eight PM and a hundred orders come in. If you don't fill them all, and fast, you are in big trouble. There's a huge temptation to cut a few corners, omit one or two subtle yet vital steps. But if the head guy is there, and he sees you, you'll have cut yourself out of a job.