It's not really just a guessing game. A skilled goalkeeper can read a player's body language to try to figure out which way they will go. Also, MLS used to have shoot outs like you described, but they axed them because no one else in the world does it like that. I have posted a video of this below for your viewing pleasure. As you can see, it does give the GK a better chance of stopping the kick though. This was San Jose's 4th shoot out in a row in only their 5th game, and they would end the season with 12 because games couldn't end in ties at the time. Cameos in this MLS relic include an obnoxious amount of the "charge" cheer, the squad # 0, and a goalkeeper wearing a baseball cap. Aodhan Quinn's father was San Jose's coach that year.