I am big fan of "cost monitoring". In my previous company I had a good setup for costs monitoring - including release to release comparisons, drill downs, stat

I am big fan of "cost monitoring". In my previous company I had a good setup for costs monitoring - including release to release comparisons, drill downs, statistics, etc. After each release I looked at this data. It saved a lot of $, by simple fixes like "why we are calling this API twice?". It also quite some issues that weren't strictly customer related, but weren't apparent from other type of data (you will always have some "unknown unknowns" in your monitoring, and costs data seem to be pretty wide net to catch some of those)