I usually try to find something special in each of the guys that I see.
And I have to agree that my ATFs are the ones that I see monthly or more often. Seeing guys that often, you build a rapport and usually even a friendship.
I'll chat with those guys OTC as well. I'll PM just to say hi to guys that I've seen before. And the guys that reply are the ones that have potential of becoming ATFs, even if we don't set anything up. It's more than BCD activities.