I recently purchased a professional-style milkshake mixer, and some recipes I've researched say that adding ice cream is a must for making shakes, along with adding a few drops of milk. But some of them also say to add vanilla extract as well, usually a drop or two.
What's the purpose of adding more vanilla to the shake if the ice cream is already vanilla? Wouldn't it just make sense to skip that and add any other flavour, or keep the ice cream and milk flavour intact?