There are three parameters for an arrow that are important,
Dynamic spine is number is most important and it is because of archers paradox, as the bow string moves forward it transfers energy to the arrow and the rate of energy transfer is dependent on many factors. However these can be quantified by many arrow selection programs and is dependent on draw length, draw weight, and bow geometry (brace height etc.) You can have 4 types of 60 lb bows and all will provide differing amounts of energy, the more energy provided the stiffer the arrow must be.
As the string moves forward it is pushing the nock towards the tip. the arrow will compress slightly, flex, and/or yaw.... the compression is negligible and does not affect arrow tip/nock alignment. So arrow can either flex or yaw... too stiff arrow yaws and pushes tip off axis. perfect flex and tip stays in alignment, too much flex and the tip gain comes out of alignment so you are trying to find a node where tip is in alignment with least amount of flex because too much flex and arrow can snap in bow with bad outcome.
Adding weight to arrow can affect this especially on the tip. The flex is created by the arrow overcoming the inertia of the tip which is why adding tip weight affects tuning. I shoot many different arrows based on purpose and they all have same dynamic spine but most commercial arrows are built to be effective for hunting with a 100 grain broadhead in a compound bow. this is the 30-06 180 grain bullet equivalent
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