It may be more cost effective to use the same db instance, but that has it's own issues, like 1 site dragging everyone down, all sites need to handle the same d

It may be more cost effective to use the same db instance, but that has it's own issues, like 1 site dragging everyone down, all sites need to handle the same db version and upgrade together.. I guess it's also just more instances to manage in total, instead of 1 + n it's 2n. You _could_ run the dbs on the same instance but not using the same DB process, via containerisation perhaps. That way you could reduce your instance count while still keeping (somewhat) operational separation..