[zedpm]

It isn't a matter of getting to a certain scale before you use RDS, if that's what you're asking. The value of RDS is streamlining and automating db administrative tasks. If you want to update from Postgres 11.5 to 11.6, for example, you just change that setting on your RDS instance and it happens, either immediately or at some scheduled maintenance window. I f you want a hot standby in a separate availability zone, it's trivial to add one. Read replica? Trivial to add.

In general, I've found it makes sense to pay the premium for RDS and spend my and my team's time on more valuable work than db admin tasks.