Liquor isn't very different from produce in the perspective of cost fluctuations. You have seasonal trends in the drinking patterns of your customers and so you try to accommodate that with drink specials. Also beer and liquor distributors run specials so you try to by product when costs are down. The most controllable variable is the actual server to customer interaction. This is where I come in.
Servers have the ultimate responsibility and ability to control costs.
Through promotional selling they have the ability to rotate stock more quickly and push items that will make the most profit for the restaurant. By giving the guest only what asked for and not asking if they would like a refill the server can save the company money at every table. If the server has been trained right savings can be obtained through a reduction in order misrings and mistakes. If an order is taken wrong at the table and the mistake isn't caught until the food is served to the table then two things can happen. First, the customer's dinner may have to be remade producing a rise in labor time in the kitchen or the customer may say they will eat it anyway, causing a loss in customer satisfaction.