Honnold had practiced individual segments multiple times before this attempt. Those practice runs had left rubber marks on the walls, which helped him in following a specific route. Before attempting the complete climb, Honnold verified that the rubber marks were not removed by the rains. Plus, he has a daily regimen of specific exercises, so many freeclimbs before, etc. A complete professional, not an idiot for sure.

Here are more details about this climb and his preparation: http://www.nationalgeographic.com/adventure/features/athlete...