Imo it depends on the type of change required. If it involves churning out 1000 line of new boilerplate, an LLM will win every time. If it means tracing a subtle edge-case bug and carefully planning a deep one-line change in a 100k codebase that leaves all other behaviour unaffected, I would still expect an experienced dev who's deeply familiar with the code to do it at least as fast and more correctly first time.