That alone isn't an indication of lack of coordination. Lack of communication perhaps.
I think we are now aguing semantics. How does one coordinate without communication?
I've flown with some folks that were so on-the-ball they never needed a check6, and they pretty much knew this about each other. Then I've also flown with some verbose folks that give 'em freely on vox.
I don't know anyone who is so 'on-the-ball' they never need a check6.
When I flew it was about 5 allies vs 10 axis it is common sense if you see a P47 currently engaged with 2 opponents (zeke and 109) and a 3rd sneaks in...you check6 them. I was handing out check6's and vox warnings just as I do on the axis side. I'd rather have 15 check6's when I already know the guy is there, than be cherrypicked because someone is afraid to hurt my feelings. I'm sure most would agree.