Why do many recipes instruct you to oil or grease the pan at the start of the recipe? I've noticed that most recipes that end up in a pan in the oven will have me grease or oil the pan at the start of the recipe. This is long before I have anything else to put into it. The pan just sits waiting for me to do the rest of the recipe. Here's just one example: http://www.wholefoodsmarket.com/recipes/3073

Why is this? I'm partly just curious and partly interested if I can leverage this some more.


Does the grease (or oil) work better if it ages in the air? If so, what is the ideal time for aging?
Does the recipe author just want to be sure that I have a pan and some grease that I can use before I prepare the rest of the recipe? If so, then I think I'll just wait to do it.
Is it to make sure the pan is cooled to room temperature by the time I get to it, in case it came from the dishwasher?
Perhaps a historical reason?
There are three good reasons to oil your pan beforehand:


Your pan needs to be ready as soon as your batter is.  For cakes, the batter can fall apart while you are greasing the pan.  This is especially true for cakes that have air whipped in, such as genoise, which can fall apart in a few minutes.  Recipes containing baking soda can lose their fizz in this time too.
You can't forget to oil up the pan.  In the heat of the moment, it's very easy to  forget to apply lubrication before transferring the batter/dough; inevitably this wrecks the recipe.
Greasing the pan is part of baking mise en place and should be done before main cooking.  Mise en place is a key principle of professional cooking, and means "everything in place." The idea is that ingredients should be prepped and ovens preheated, so you can do the actual cooking efficiently.