For the really skilled Civ 5 players, they play the game like professional chess players. Professional chess players must make their move quickly. In fact, i think they are timed for the length of their decision making process. These professional chess players are able to make quick decisions because they have played gazillion games already, so they have already seen the possible patterns that can emerge from the current configuration on the chess board. Expert Civ 5 players are like that. They make quick decisions because they are so familiar with the game, and they have honed their strategy through thousands of hours of playing, so they don't even need to think anymore.