There is a special feature in In-Portal (that I bet nobody knew about) that allows each system setting have it's own validation logic, e.g. be always required or allow only numbers.
To use it you need to place serialized array of field validation options into "Validation" column of that system setting.
Because of we are not using this very often (I think we should start using it at some point) error, where validation logic from system setting A is passed on to next system setting in same subsection was unnoticed for a long time.
For example you have 2 system settings one after each other:
- Site name
- Session expiration timeout
When you apply "required" validation to "Site name", then "Session expiration timeout" settings become required too.
Ready for testing.