At some point the opponent knows that you know he knows you know that he knows you know his next move.
I do think that there are a certain number of moves you can do in a certain situation, which doesn't throw the game away. Being unpredictable is playing the one which they think you won't, from what they can see and how you usually play.
If you are in a losing position, then play unpredictably, if you are in a winning position, play predictably and secure the win without doing anything stupid. Also you can never know if they will know what move you are going to do, depending on how much they have thought through and what is normal and unpredictable play for them