There Is No Kill Like Overkill: Usually averted by the Imperial Military Service and those following its fine military tradition – although that tradition also suggests it’s a good idea to have it available to use. Because it’s unsubtle, and inelegant, and for a sophisticated people of great strategic acumen, therefore… kind of tacky.
That said, also occasionally played very straight when it’s time to Make An Example Of Them, and see most of that list of examples for specific cases.
That said… your standards for overkill may vary.
(For example, it’s always cheaper to fire a KEW out of a mass driver than it is to go to the trouble of assigning a legionary, a cutter, a pilot, etc., to go dirtside and take a bunch of time to hunt down and shoot a target individual personally.
What do you know? Turns out that crater was the fiscally optimal amount of kill after all…)