[10000truths]

I think it's natural to be uncomfortable with black-box optimizations with unclear boundary conditions, especially when there's no escape hatch or override. Postgres's query planner is notorious for this - some small change in a table's computed statistic shifts the cost estimate ever so slightly to favor some other "optimization" that actually ends up performing significantly worse. It happens rarely, but no one wants to "rarely" be paged at 3 AM on a Saturday.

Optimize for the p99/p99.9/worst case scenarios. Minimize unpredictability in performance where possible, even if it comes at a small cost of median/average performance. Your SREs will thank you.