There exist a wide variety of ways in which to design missions for Warhammer 40,000, Warhammer 30,000, Age of Sigmar, and all manner of other games. One of the defining features of the Games Workshop approach to mission design is that there is no "automatic win" button. In some war-games, the killing of the general might represent an automatic win condition and the game would stop at that very instant. This generally does not happen in 40k.
Indeed, the closest thing to an automatic win is usually (but not always) a complete massacre of the opposing force.
When this condition is met, the winner usually is considered to have won the "primary" mission. Arguably, they have also secured all of the secondaries and perhaps tertiaries (if they are being used) as well.
But herein is the point that I want to make. If the winner in a massacre is presumed to have achieved maximum points, what about the loser?
In our recent tournament, we designed it so that both the winner and the loser had things to still play for even late on in the game.
For those people aiming for a massacre style victory, we awarded one additional point for achieving this goal. Hence we had some players attempting to avoid being completely massacred just for the sake of not giving away that final tournament point to their opponent if at all possible. This is a good thing and reflects not wanting to give up. Added to this, we implemented secondaries and tertiary missions that could be achieved even if a massacre victory was scored against them.
The most obvious one is "Slay the Warlord". This can be achieved even if one is massacred (and obviously happens by default if one is victorious in a massacre victory!).
Another is "First Strike" -- this is the same as first blood, but either player can achieve it. All they have to do is kill an entire unit in the first turn of the game. This not only alleviates the bias from achieving first blood from who goes first (which is undeniably a huge contributing factor), but gives both players something to aim for.
Other examples include moving a particular unit to a particular destination during the course of a game. This can still happen for anyone who subsequently gets massacred.
Hence, when designing missions, we like to frequently include at least one or two (secondaries or tertiaries) that can be scored by someone who eventually gets massacred regardless. It still gives people something to play for. Of course, there are still aspects of the game, such as having a unit in the oppositions deployment zone at the end of the game, that cannot be achieved if one is massacred. Instead, perhaps award a secondary or tertiary for moving all of ones own units out of their deployment zone (and thus score secondaries that way) rather than depend on the state of the game on the final turn. In this way, both players have things to aim for that they can achieve tournament points for during the game, and not just at the end. Meanwhile, having that extra point for a total wipe out victory will drive the win-at-all-costs player onward, and probably to distraction (as we experienced the other week!).