I put the terms in quotes because it can be as simple as a set of prompts you develop for various contexts. It really doesn't have to be too heavy of an idea.

I think overall you're better off creating these yourself. The more you add to the overall context, the more chance of the model to screw up somewhere, so you want to give it as little as possible, yet still include everything that is important at that moment.

Using the agent and seeing where it get stuck, then creating a workflow/skill/whatever for how to overcome that issue, will also help you understand what scenarios the agents and models are currently having a hard time with.

You'll also end up with fewer workflows/skills that you understand, so you can help steer things and rewrite things when inevitably you're gonna have to change something.