How does Pistons priority work? [duplicate]

I have two pistons facing each other. Powering both at the same time from the side can give different results based on where it is being powered from. I have absolutly no clue on the pattern and how to use it.

How does it work? Here is an example of an experiment:

As you can see, the center pistons are biased based on the side as well as the right one. The left one will have the same bias regardless of side powered.

I decided to make more tests and here are the results:

Each line is a pair of pistons. There are two rows of experiments. The block above shows which side he is biased towards. Orange (Granite) means powered from the left side and Gray (Andesite) is powered from the right.

For example, the top left most (first red stroke in next pic) has both blocks on top of each other, meaning regardless of side, the piston closer to the camera is powered.

The three pistons from picture 1 one and 2 highlighted

And here is the question:
How does this rule works? With all this experiment I got 0 answers. My goal is to have the far most piston from the source (Torch in case of pic 1 and 2) be activated first, always.