I run whole board of races and am certain I get everyone thats still active ,,you can check to see who has logged in recently , also you can check status of credits earned -I am more likely to run lower lvls with low credits to help them out than grind higher lvls that use Bob for a bank ,,unless its a reciprocal agreement made in advance .
Its normal for friends to give it a rest for a bit .So it pays to try to help the newer gamers who have yet to melt their PS3 yet.