It is easy to burn real money on a batch that was never going to work, and find out only after it finishes. I have done it. The fix is boring and it has never failed me.
Before the full run, I do three things. Set a budget I am willing to spend. Run a small sample and actually look at the outputs, not just the exit code. Wire a hard spend cap into the job so it cannot run away.
More than once the sample killed a run that looked completely ready. The prompt was subtly wrong, or a source had gone stale, or the cost per item was triple what I assumed. Catching that on a hundred items instead of a hundred thousand is the whole game.
The rule: if the small sample does not earn the full run, the full run does not happen. The cap is always cheaper than the lesson.