The top dart players are extremely good at throw actions that are the same. The distance from their throw to the triple 20 will be very close to consistent.
Human beings like consistancy, dualities, the stereotypical order and regular patterns to hang off. Randomness puts a bit more needed processing into the game.
What if the dart board scoring areas were a projection on the sisal? This means the areas can be varied at will. Areas could be altered relative to scoring amount. The position of the smaller higher scoring areas could be placed scientifically for the handedness of the player and in the most difficult trajectories. Circles could be the areas' shape but I don't see why this couldn't be changed. The colour of the areas could also be varied.
"Come on Alicia, I bet you can't hit that purple pacman ghost."-- wjt, Feb 11 2017 //Pollock// That would be a different kind projection, one involving watching the board areas change with two many drinks on board.-- wjt, Feb 15 2017 random, halfbakery