The variables are access, distance and blockage type. A blockage in a rear-garden chamber with a gate wide enough for the jetting hose is far quicker than one under a paved-over manhole that has to be located first.
Where the blockage is severe — a full fat deposit or a root mass across a joint — jetting and then re-jetting after camera inspection is normal, and is the difference between a clear pipe and a temporary hole through the middle of the obstruction.
If the engineer clears the run and the water still does not move properly, that indicates a structural defect and the visit becomes a diagnostic one.