Increasing the board size is a kind of small progression. If you go from a 9x9 board to a 25x25 board, your robots will make a lot of unnecessary moves at first, but once you have a lot of robots, you should be able to earn coins immediately, even on a 25x25 board again. Of course, increasing the board size is a loss compared to the immediate gains, and this is an area of game design that needs to be improved.