Dunning letter frequency

I have question on the dunning letter frequency.  The invoices age changes every day when the date passes by.  If we schedule the dunning letter generation program, it generates letters for the delinquent accounts on that day.. correct?

If yes, can we schedule it to run once a week on a particular week day?  In that case will it pick up all accounts which became delinquent from the previous run?

Thanks
Raghu