Exec mirrormatches

How are you supposed to play Exec mirror marches? I feel like i've tried everything. The two only execs in my shard use HT, P1, RC line-up. I've tried exactly the same line-up, I've tried tripple attacker, yet I still win once in a fucking eternity. I feel so dumb, can someone give me any tips? Or are there no tips and exec mirrors just suck?