I would say that it is like gardening. If you let them go havoc from the start, the weed will take over. If you keep focusing on removing the weed and enforce specific standards and practices over the code base and it keeps growing, over time LLMs start to suddenly follow that and they don't make so much slop anymore. At least that is my experience. But I force specific audit agent after every added feature which says them to force compliance with AGENTS.md and check the consistency with the code base.