I've been in situations before watching a con creep up my 6 with several friendlies behind, thinking to myself, "I wonder if any of those guys are gonna send a check six?"
When they don't, they were using me as bait and thus are dweebs.
Don't expect anyone to watch out solely for your best interests. I probably only spend 30% of the time looking forward, 10% out my 3 or 9, and 50% to my high/low six. I get blamed a lot for not checking someone else's six.
Guy screamed at me the other day on range, about not giving him a check six. He got bounced about 2.5K away from me (I think). He cursed me up one side and down the other asking why I didn't "check six".
I replied, "The red P51 that was 1000 off my 730 diving from 12K was my only concern".
He didn't reply back.