Every time I think I've mastered Settlers, I discover yet another novel tactic or strategy. This time it's Robber placement.
I've usually selected robber placement based on a combination of factors, including who is winning, which hex reduces the most dots worth of production (x2 for cities) that isn't mine, several variations on which resources are scarce, whether a 2:1 port for an abundant resource is occupied, and trying to take a card I need from a player I think likely to have it. Which of these factors to emphasize for any given robber placement is a fairly complicated decision that depends on what stage of the game you're in, how much the leader is winning by, and what you're needing next.
All this is standard stuff for those who have played more than a few games. But I just ran across an idea I hadn't heard before:
When not trying to stop someone close to winning, nearly always place the robber on the most valuable hex of the person on your right only. The reason for this is that this person won't be able to retaliate for at least 3 rolls of the dice (in a 4 player game), while the other players may be more favorably disposed to you for not getting them. And if this player (to your right) retaliates, it is immediately your turn next giving you a chance to possibly roll a 7 or play the robber (if you have it). So assuming robber retaliation is somewhat predictable, this seems to be a sound strategy.
I don't have a strong opinion yet on how well the person-to-the-right robber placement strategy works - as I don't know how predictable retaliation is in general or with the specific groups I play with. But I do now wonder:
For advanced Settlers players, what is optimal robber placement? Is it this player-to-the-right placement method (because retaliation is mostly predictable)? Is it the standard tactics I listed above? Or are there different and perhaps more subtle tactics for Robber placement I haven't even thought of?