Question on Alternative Assault Resolution

[Strela]

You should absolutely continue to fire artillery at bunkers and hard targets due to the following rule. I have seen units disrupt in bunkers with a no effect!!

Special Disruption Rules
As a result of being fired upon, the target unit may have to take a morale check
to determine its Disruption and Broken status as described in the section on
Combat Results. There are some modifiers to this effect:
• When an indirect fire unit fires on a Hard Target, either hard vehicles or
units deployed in a hard fortification, then the disruption effect is twice
that of normal. For hard vehicles, this is the effect of causing them to
"button up" and thus have reduced effectiveness. For hard fortifications,
this is a result of the "pounding" that results on the fortifications and the
disruptive effect this has on the occupants.