Stats would suggest that if you dive to 1 side every time, you'll save 33% of your penalties... Pick a side and keep going their if you're a keeper! Stop changing...
When it's 12-11 in a penalty shoot out.. I don't think that'll matter People have fav sides and wont swap.
Surely the options are right top, right bottom, left top, left bottom middle top middle bottom. Which means the best thing for a keeper to do is stay in where they are as they cover 2/6 of the options rather than 1/6