There are times where there's something I want, but won't get it unless it happens to be convenient while getting things I need. Like ice cream; on my way out I'm going through exactly 1 frozen food aisle and if there's something else I want to check that's not in the ice cream aisle, then I just don't get ice cream (and if I do go through that aisle and I'm still unlikely to get it unless its on sale). The exposure only matters because being exposed to it means its convenient, not that I suddenly want something I hadn't considered.