Personally, for some of us newer players, It's difficult for us in certain situations to determine who is in front of who, and which way the Con is going versus the way that the friendly is going. So yes I do try to throw check six calls if I see a con extremely close to a friendly. Some times they already know about him, sometimes they dont...
And I know in my mind. and remember im still rather new, so Im still adjusting, but If Im in a group of planes chasing down a con, who is chasing a friendly. I personally believe that one of the other friendlies have already thrown out the Check Six. I dont bother with score. Nor Do I care about getting the kill, I normally try to jump in and help anyone who I see in trouble. And I believe alot of others do also. But of course it could just be the country I fly for or perhaps the hours that I normally fly. (Bish, and Late) but I dont normally see friendlies just floating around and watching their fellow countrymen die with out trying to help in some way.
But what does bother me, is when Im in the midst of my own fight, and I happen to swing around and catch a glimps of a con just about to engage a friendly.. I throw a check six, either through vox, or if Im still able to. The ' key.. And it just so happens that the call came a moment too late, then I have a friendly becoming quite irate with me because I warned him too late.
So to those of you out there who get upset because someone doesnt throw you a call in time, Someone else already said it here. "Your Six is your responsibility"
But hey.. Thats just how I see it