Of course you're right, but that doesn't change the overall picture. That could be 13.2 shots per day for 44 square miles, or 19.8 shots for 66 square miles.You can’t just divide frontage like that, that’s not how artillery is applied tactically. Mass and concentration are principles of the defense.
The radius of destruction of the most super-high-precision projectile does not exceed the radius of destruction of an ordinary projectile of the same caliber with the same explosive - because in the volume of Excalibur part of the space is occupied by the "brain". Shooting 5 shots a day instead of 20 in 66 square miles, the maximum number of hits you can get is 5. Not 8, not 15, but 5. And that's not a lot - it's catastrophically low.
Excalibur is a beautiful thing, but wars are not won by snipers, they are won by machine gunners.