Depends a lot on the way people use them.

If you discusses a plan with CC well upfront, covering all integration points where things might go off rail, perhaps checkpoint the plan in a file then start a fresh CC session for coding, then CC is usually going to one shot a 2k-LoC feature uninterrupted, which is very token efficient.

If the plan is not crystal clear, people end up arguing with CC over this and that. Token usage will be bad.