a model capability is never going to fill in an unknowable blank that a custom skill (or whatever equivalent your paradigm supports) can.
a model might have the cleverness to whoami and look through the .ssh folder for keys and evidence of past connections when asked to connect to bob, but a skills file can just easily say "We connect to bob using key Z and user X." so that the operation gets done without all this nonsense needless inference as far into the future as the information is valid for.
a concise information dense skill is going to always dominate on tokens-burnt for any given task that requires insider knowledge. it simply gets rid of the entire investigative phase of work.
But, for custom use skills, ofc no model will be able to replace them and it's not efficient to try to do that as well. For this type of skills I create and maintain them by myself, my question was about "general use" skills, they are everywhere on the internet, how do you manage them?
This of course is from my own experience writing code, where agents are already good at software engineering conventions. This probably doesn't hold as well for other tasks, say writing marketing copy with a unique voice
For now, I keep skills pretty minimal - single sentence prompts I send all the time, like "Remove all the slam poetry from the docs in this repo."
I also tend to share often. All skills go into a repo my team can access. No pressure, use them, riff on them, add your own - sharing and engaging on how we do the work is more important than making everyone do the work the same way to me.
it has all the skills/docs my particular application needs
i treat it as ADRs as it helps the AI understand the parts of the system it is working on