Well, that really depends on what your goal is. One reason for prolonging the game is that it gives your opponent more chances to make mistakes, turning some l

Well, that really depends on what your goal is. One reason for prolonging the game is that it gives your opponent more chances to make mistakes, turning some losses into either ties or victories. This is true for both human or AI opponents. Another reason to prolong the game against human competitors is if you're playing another game after this one, and you think your opponent will tire before you will. By causing the game to go longer, you gain a mental advantage in the next game. Now, these may be considered "unfair" or "unsportsmanlike", but explaining that is left as an exercise for the reader.