Limping heads up is another tool to use. The goal in heads up is not to be predictable. So limping mixes up your game.
Being unpredictable is advantageous when hu, but can lead to difficult decisions. Limping with AA and expecting a raise that doesn't happen, raising with junk and getting reraised,
re-raising with junk and getting jammed on, all happen with enough frequency to make you want to play ABC poker and let the cards play themselves. I think that unpredictable play should include the straight forward raise good
hands, fold bad hands, type of play. Folding preflop in a hu game has somehow become an unpredictable part of my game that causes my opponent to start to fold preflop as well. Fold preflop from the button? Outrageous ! But the unpredictable play can entice your opponent to be overconfident and destroy themselves.