I know it seems like an inconvenience but take advantage of the longer refresh time by visiting as many shops as possible before the refresh. Reason being, most farmers(that I visit)don't simply put one item in their shop to sell. They place an ad with one item but may have something else of interest, might even help you complete a boat shipment. Most of the egg ads I review are selling more than eggs. I picked up 10 items of sugar which sent my boat on its way quicker than originally planned.
Keep in mind everyone doesn't know to remove the check mark when placing items in their shops so the items do not display in the newspaper. I forget sometimes myself when I'm rushing.