In a typical garagehood configuration you have a choice of 5 targets. Two direct neighboors (left and right) and three across the street (front-left, front-center, front-right). Some garages are known to be not visited during winter, those you can shovel all day every day. Some belong to high-rank members, those you want to try to respectfully avoid. You would shovel direct neighbors only if you are in an open conflict with them. The usual target is typically front-left and front-right, they are not too far away but not in direct contact either. If you are on a street end, then you must shovel to the side but avoid blocking the road for the next street.
To answer your question, the enemy must be within reach of no more than 2 shovel throws.