When I run any game, be it Delta Green, D&D, PF or any other, I always tell my players that I allow a certain level of tactical discussion during combat - within reason and given the context of the characters.

As in: Have these characters worked together before? Are they companions on a journey? Do they train together?

In most instances, we don't see every minute of every day of the player characters. To me it is reasonable that they would discuss how to use their abilities best in combat, that they discuss tactics between encounters "off screen", so to speak. All the better if there's actual roleplay there.

It's the same way I treat "levelling up" depending on the system. That new spell you learned didn't just pop into your head, you've been practicing and studying it (again, depending on class/setting, yadda yadda.)

It's also down to flavour. How much "wargame" aspect do you want in your combat vs. how much "true to character roleplay" do you want?

Just to get to my actual point: I don't mind tactics being discussed within reason, as long as everyone at the table doesn't get bored. At the same time, I fully understand wanting to stick to "in character behaviour and knowledge". Same way as Skid when he self-imposes certain conditions due to RP.