Especially in Italy with its vertical, spiny terrain. One of the recurring themes in Atkinson's book on the theatre is that success or failure often depended on the outcome of dueling Forward Observers. In Normandy you have more restricted FOVs, presenting geometric puzzles to solve. The Russian campaign offers, generally, flatter ground so there should be less of a feeling of attacking exposed on a well lit operating table.
Or, artillery may deserve a tweak in the direction a bit less lethality or a bit less precision, or both.
Or maybe BF nailed it.