I don’t see how culture, in a broader sense, can be ruled out as a factor of military performance.

Organizational and political mind-set is also a type of culture. The military its self can be said to be a culture.

The world view of a people or a state can effect training and doctrine. Authoritarian governments may discourage initiative and inventiveness in their officer corps.

Likewise, training and tactics can be effected by culture in both a broader and narrower sense.

These biases can lead to improper training methods and miss judging situations.

I think most of us have heard of the war averted because of bullet grease. Was that other than cultural?