i can't say that it's shaving from my point of view.
some sites r overexposed to the limit, some - almost, some r rather ok.
i was doing 1:1000 with one of their sites in september, 1:200 with the 2nd and 1:200 with 3rd. right now 1st one is 1:3000, 2nd - 1:1100 and the 3rd - 1:200.
they r really pushed a lot, esp. with their super-aggressive referral program. right now everyone and their pets r promoting 'em, if only i (a small wm) am sending about 1000 hits a day, i can assume they r getting about few millions of hits daily and that's really a lot for 13 sites.
p.s. don't forget about their '4 hour cancel' rule