[Imp]

I would assume 2 cover the frontal arc & 2 the rear given the 150-180 coverage arcs.
Potentialy I would say 2 would cover any arc & activate unless they talk to each other & the second does not fire.
Incoming shot from the front angled like so /
Closest sensor fires first on the right front, projectile continues and enters the sensor range for the left front so it would activate unless told not to.
Best case each arc talks to each other & in overlap zones it can respond 4 times if only one fires.
Possibly more likely is 2 times through the same arc, both fire & have one reload.
It could react more if fired on from diffrent arcs.
Assuming 2 shots from the front followed by a third from the side.
The front unit covering that arc would be out of ammo but the rear unit has not triggered yet so has ammo to fire.

This reminds me I would love to know how useful is modern artillery versus modern armour?
Not talking with regards to destroying but its effect on protective systems, vision aids & targeting.
Versus a dug in target I would have thought while it might not destroy it a high overpressure attack such as thermobaric could kill the tech.