That's the way we've always played it. Bonus if target not entrenched, negatives if reduced or 3+ hexes away from French ground unit.
My VM opponent never brings his reduced troops up to full strength until he's ready to attack again, & there's little or no reason for the VM to have troops not entrenched. So practically speaking you might get lucky & roll a 6 for an entrenched full-strength VM battalion if French guys are on a really nearby entrenchment (since it happens before French tactical move) but overall it seems pretty useless.
The airforce seldom had any effect, but now and then, they managed to get a strike right on target. And it's free.