When making a pie, you almost always have to make holes in the dough with a fork. This is called docking.
What is the exact reason for doing this? Are there kinds of pastry (puff, short crust, flaky) where this isn't necessary? Do you only need to do it when blind-baking? When you're using baking weights, does it still make a difference?
Doughs are docked to keep them from blowing up with steam while they bake.
Thus- you only do it in applications that you don't want blown up- like blind pie crusts. Puff pastry applications, for example, you usually do want to blow up so you will get a lot of light layers.
If you are baking a pastry with a filling then the filling will keep this from happening. If you are baking blind, even with pie weights, you should dock because the weights might not weight evenly and you might still get a bubble.
I can offer an example from work experience. When making flatbread, I shared this with a co-worker. We were docking the rounds to keep them from puffing up like little pillows, for this we want flat breads that are flat. Docking correctly allows for small "pillows" of air, yet the overall product does not rise much. I baked one without docking to demonstrate how that flatbread would turn into a pita. The entire thing puffs up, separating the top and bottom layer, creating a void. Once cooled, a nice pocket is there for sandwiches. I know this is not a pie answer, but I hope that the visual example helps explain why we dock.
Docking is used in order to get the air bubble pockets out of the crust. Depending on when the dough was made, to the temperature of the dough itself, you can use anything to dock a pizza including your fingertips as if you are clawing at it. It is the same as edge stretching except you are putting holes in the dough to release air and gases.
