I've had my hair on fire because my app code shit the bed. I've never ever (throughout 15 years of using it in everything I do) had to even think about Postgres, and yes, I always set it up self-hosted. The only concern I've had is when I had to do migrations where I had to upgrade PG to fit with upgrades in the ORM database layer. Made for some interesting stepping-stone upgrades once in a while but mostly just careful sysadmining.