SLIGHT INITIATIVE. Marginal Revolution reports on game-theoretic research applied to grandmaster chess. Grandmasters employ mixed strategies in their choice of opening. They may have also discovered slight advantages to the first move. Although the modal outcome is a draw (61 percent of world championship games since 1951) the player with white pieces has won 26 percent of the games and the remaining 12 percent of the games (rounding error, guys?) are wins for the player with black pieces.
I can offer at least anecdotal support for players using their favorite strategies in non-repeated encounters. Bobby Fischer, in Sixty Memorable Games remarked on a favored exchange sacrifice against a castled King, "I've made this sacrifice so many times I feel like applying for a patent."