Maybe I'm just really lucky but reading those instructions it's basically how I find Claude Code behaves. That repo with 4k stars is only 2 weeks old as well, so it's obviously not from a much less competent model.
Same here, I find most of these skills/prompts a bit redundant. Some people argue that in including these in the conversation, one is doing latent space management of sorts and bringing the model closer to where one wants it to be.
I wonder what will happen with new LLMs that contain all of these in their training data.