Most insurance companies, including BCBS, remit payment monthly. Now they are extraordinarily picky on claims. They will reject it for even the slightest thing being off which is their way of slow paying on many claims.
Typically within 30 days claims are filed and if kicked back have a 90 day window to be re-submitted if I am not mistaken.
So, altogether, usually within 60 days they have had claims submitted and paid (up to 30 to file and 30 to receive payment).
They usually just send one large check for the total claims filed and approved for a certain period.