You cant lose whole army to it, unless it is concetrated in one enemy sector and just sits there, not capping it. If sector starts getting capped/decapped, then ability won't target it anymore.
Maneuver with your troops, spread the attack to other sectors.
The ammount of shelling is nowhere close to Sector arty, and it won't speed up, as sector arty does.
TLDR: l2p
Ok thanks for telling me to L2P Mr Rank 1400, very constructive.