by gamercab
I like the point of the number of players affecting the usefulness of this strategy. However, I think mobility may be even more important during games with 4 players.As someone else pointed out, having someone right near a danger city is great, but you might have 3 turns before they can act.
When you are playing with 4 players your odds of getting 5 cards of a color in a single hand are lower since the cards are spread over more players. The result is that you will likely need to do more card trading. The extra mobility of the research station network makes card trading much simpler. In a 2 player game you know you are going to have excess cards that you are forced to dump at some point, so using some to fly places is less damaging to your curing than in a 4 player game when you may not have determined which player has the best odds of going for which color.
There are other ways to deal with card trading of course, depending on what characters and upgrades you choose.