Most AI projects that fail do so before any code is written, because nobody agreed what the system was supposed to replace. A chatbot on the homepage is not a use case. Handling the two hundred enquiries a month that currently sit in one inbox is.
So the work starts with a baseline: how long the task takes today, how often it goes wrong, and who picks up the pieces when it does. Without those three numbers there is no way to tell afterwards whether the integration helped, and no way to decide whether it is still worth keeping when the model pricing changes.
The industry pages below go sector by sector, because the honest answer differs sharply between them. Document handling in a law firm carries a different cost of being wrong than drafting listings for a rental portfolio, and the two deserve very different amounts of human review in the loop.