You can absolutely prompt agents not to write tests, or not to write extraneous asserts, or whatever, and I find that generally quite useful for the kind of cod

You can absolutely prompt agents not to write tests, or not to write extraneous asserts, or whatever, and I find that generally quite useful for the kind of code I write. I don't think it's "months of users training it", it's more that a lot of people do want a one-shot agent, and having a good test set really helps that.