Once you have a new offer up and running and pretty much tweaked everthing you can to give you just about the best ROI you can pull what would be your cutoff point when deciding to continue running it or use your resources for other things with a better ROI? Many people I know say to leave it running if it's in the green at all while others say not to waste the resources (time, energy, money) if it's anything less than 100% ROI. What would be your magic number to keep running the campaign?