Stack vs individual unit fire

[Kool Kat]

Without any actual evidence I have always felt that firing a stack combined has a greater effect than individual units, the downside is that you get less shots and hence less chance of a disruption shot.

Gents:  

That's always been my impression.

When I volley fire an entire stack versus a single enemy unit, there is a higher casualty rate with the enemy unit then if I fired individual units against it.

Now, I don't know if I added the cumulative casualty rate of firing individual units versus a single enemy unit - would it equal three stack volley fires?  It does not seem to hold true here.