The G3's third turret privileged broadside fire

Was the G3 battlecruiser's third turret nearly useless from some approach angles?

Its placement made sense for broadside fighting, but dependence on broadside arcs remains a design weakness.

The third turret was intended primarily for broadside fire. That purpose explains the layout without eliminating the viewer's criticism. A capital ship designed around the broadside can lose useful arcs when the tactical situation demands end-on fire or rapid maneuver. That limitation weakens the G3 arrangement despite its other strengths.