The three release mechanisms
Original B/L (OBL): a negotiable document of title. Cargo releases only against surrender of a signed original at destination — maximum payment security, used with letters of credit and untrusted counterparties, but originals must physically travel, and a courier delay can hold a container past free time.
Telex release: the shipper surrenders all originals at the origin office, and the carrier (or NVOCC, on its HBL) messages destination to release without documents. It preserves the shipper's control up to the moment of surrender — useful when payment lands while cargo is on the water — then removes the courier risk.
Seaway bill (express release): no originals exist at all; the named consignee takes delivery against identification. Fastest and cheapest, zero title control — appropriate for intercompany moves and long-standing trusted relationships.
How desks choose — and where it goes wrong
The choice is a credit decision disguised as a documentation option: how much control does the shipper need over release, and until when? Common failure modes: issuing a seaway bill before payment terms justify it (control is gone the moment it's issued); missing the SI cutoff so the B/L can't be finalised before departure, which delays the telex; and forgetting that on consolidated cargo, HBL and MBL release are separate events — a telex-released MBL does not release the HBL cargo to the end consignee.

