The short answer is it may not be needed - and there is a tendency to always use banjos and bolts, even in cases where an internal nut like a Prihana would be better (as no need for extra holes in the box) Partly I think because the glands are often sold with a banjo or two in the packet, rather than it being the best solution for all cases, but it saves a separate purchase. There are some house styles that do not rely on the glanded armour as the sole CPC, insisting on using a core as well, and having seen a few examples of truly dire armour termination I can see the point, but getting folk to produce a well terminated armour and cable routes that are not stressed should be enough. It also partly depends on the local inspect/ test regime - you can ask someone to give  an external lead a waggle, as part of a clean and check over without turning off the power, but verification of an internal contact is more involved.

The short answer is it may not be needed - and there is a tendency to always use banjos and bolts, even in cases where an internal nut like a Prihana would be better (as no need for extra holes in the box) Partly I think because the glands are often sold with a banjo or two in the packet, rather than it being the best solution for all cases, but it saves a separate purchase. There are some house styles that do not rely on the glanded armour as the sole CPC, insisting on using a core as well, and having seen a few examples of truly dire armour termination I can see the point, but getting folk to produce a well terminated armour and cable routes that are not stressed should be enough. It also partly depends on the local inspect/ test regime - you can ask someone to give  an external lead a waggle, as part of a clean and check over without turning off the power, but verification of an internal contact is more involved.