Are convoy routes fixed maritime choke points?

Do ports and convoy routes become predictable choke points once observation or intelligence identifies them?

Ports do concentrate traffic, but convoy routes at sea are not fixed because individual convoys can be routed and turned differently.

Ports create unavoidable concentrations of traffic that submarines might identify through observation or intelligence. Open-ocean convoy routes are less predictable. Individual convoys can receive different routings and alter course, so a published or previously observed track is not necessarily a permanent corridor. Commerce warfare therefore depends on finding moving traffic rather than occupying a single line across the sea.