Well it depends a lot on the market.
One of my ads with very good CTR has a limited audience. I can't get decent impressions bidding at $0.20.
Instead what I do is I jack the bids up...like up to $2.00. My cpc goes up a little bit, but I'm getting a lot of impressions compared to before. Guys that don't have has high CTR / CPC get pushed out because Facebook rather give the impressions to some guy with really high CTR/ really high bids.
It's pretty much my strategy for Facebook. I sacrifice a little ROI for more volume since I'm on weekly payments. Facebook is essentially bidding for the impressions. It's all about testing/tracking your progress. I'd love to bid .20 and get massive impressions but it doesn't work that way.
Hmm.. interesting but the only sacrifice is the ROI