Adam Ondra in an October 2011 interview with new Swedish website Stockholmsklättring:

I think I’m quite efficient in climbing routes in a few attempts but I do think that if I spent 50 tries or more on one route I might be able to climb 9b+¹ but certainly I wouldn’t be able to climb any harder. You have to bear in mind that when you are working on a route for a long time there is a mental barrier which you have to breach. Additionaly in reality you loose your power because your only trying a handfull of moves which means you are not training so much. You just keep climbing the very same moves and it could be true that you progress on these specific moves but in reality your shape is decreasing.

My question for Ondra:  When are you coming to America??