A winning knight on the rim
Listening to rules of thumb too often can have bad side effects
One rule of thumb is : "A knight on the rim is dim", which makes sense since a knight in a central position can reach 8 "octopussy" squares, while a knight on the rim has far less options.
A knight on the rim can even win the game all by itself. Here a fresh example, which is a nice reminder for myself to keep looking for better moves, and keep adding exceptions to rules of thumb.
My opponent offered a draw in a seemingly drawish endgame. I decided to play on, and got a winning advantage when my knight and king got stronger, and my opponent bishop got weaker. In the end there was a win but in time trouble, with some 20 seconds left, I thought it was a draw, and I "resigned" to a draw. But after the game it became clear that a knight on the rim would have won!