If you're pulling data from somewhere automatically then you should make sure to define the data contracts well and that they're not changed. Also, A/B test things if possible. I've had issues in the past where the data pipeline view of the data and the API view of the data weren't the same. Or where a bug was fixed that resulted in the values of certain fields to change.

>I'm not very sure what you mean when you say the ML results were pre-computed?

We were scoring ads per page, and possible values for both were known ahead of time. So for each ad-page combination we generated the scores and then pushed them into a giant cache.