I also allow players to roll this skill when attempting some type of special situational maneuver- positive or negative. If the roll is made, I allow the skill to be used in a supportive sense, adding the critical value to a skill.
Example: Thak and Bek have been fighting. Bek manages to maneuver to a higher ground. Thak's player asks if he can make a tactics roll to simulate a familiarity with this disadvantage. The roll is successful and the player adds the critical range to his combat skill. Thak has experienced fighting in this situation before and practiced it, nullifying some of Bek's advantage.
That is one of the ways that I allow it to be used. Charges, ambushes, etc.- all decided by GM fiat.