Is there any data to show that audience segment based advertising works better than content-based advertising? We can target an audience segment, (say men over

Is there any data to show that audience segment based advertising works better than content-based advertising? We can target an audience segment, (say men over 35) and show them same advt on all the pages I view. Or we show ads which are relevant for the content I am reading right now - if I am reading travel stories, show me travel ads. Is the concern that we won't be able to sell all the inventory doing the latter?