A skill isn't teaching a model to do the job. It's teaching it what to do in the gaps where you said nothing. Someone ran the same prompt and the same file through Claude and ChatGPT, both with skills turned on. Both shipped a deck. Neither one was asked about design. Claude picked its own colors and its own slide order. ChatGPT came back plain. It worked. Everyone reads that as one model beating the other. It isn't. Instruction-following wasn't the variable here. Both followed. What split them was the default, the taste that shows up after your prompt runs out of things to say. And you can't prompt a default. You can only write one down and save it somewhere the model reads before it starts. That's the whole thing. A skill is a text file of rules sitting upstream of the conversation, so the unspecified parts come out the way you'd have specified them. The catch is that it has no taste of its own. It has yours. If you've never actually decided what good looks like for your work, a skill just makes you inconsistent at higher speed. Type /skill-creator in the chat. Both of them have it. Most people will end up encoding preferences they've never once said out loud.