Holds on debit or credit cards are released at end-of-day processing.  Generally, holds on debit and credit cards are dropped prior to the end of the hold days as the actual transaction comes in and posts to the account.
 
With 7-day back-office processing end-of-day processing is run on Sunday, so in rare instances the holds could be dropped on Sunday.  Credit unions concerned about this change can change the number of days to hold unmatched items.