Definitely true. But in some cases it might be difficult to escalate to an higher level on lower-ROI campaigns.thats a nice ROI but that's not the best way to operate unless you're cash constrained. assuming no capital constraints most would want to maximize absolute profit (assuming you dont have a better investment alternative than AM), so more volume at a lower ROI could be better for that
Better to make 50% profit on 100k a day than 200% profit on 1k a day if you got the monies to do so.