I'd think it's a portion of each.
The recipe: (allows you to construct a spear)
You find a survivalist book that explains how to make a simple sharpened stick spear.
It'll likely include the basics below, and perhaps other advanced options to make even better spears (studs, metal sleeves, cord wrapped as a grip, etc.)
Selecting suitable wood.
The best length and thickness for what you'll be using it for.
The optimal angle you want to sharpen the point to.
Tips on fire-hardening the tip.
The skill: (governs how good the spear you craft is)
This increases with experience, or possibly more advanced literature on the subject.
How good are you at identifying wood type and quality.
Measuring (estimating) your spear length, thickness, weight.
Your ability to whittle the point to the suggested angle.
Your skill in applying fire to your spear (not too much, not too little) to harden the point.
Your comfort in trying to implement the advanced options.
-Arch Necromancer Morloc 💀