Is it still a requirement that an incremental -nojournal backup should be run 
once in a while to pick up the pieces left from the daily journal backup?

>>Yes.  It is USUALLY not necessary, but the journal service can get overrun 
>>and miss things.  

In which case if I run a -nojournal every week, what I can tell the customer 
what the expected RPO is? One week? One day if lucky?

>>Pretty much. If you're lucky, the journal service gets everything.

Regards,

Hans Chr.