What problem would a hard pencil cause if used on soft timber?

A hard pencil used on soft timber may cause the pencil to dig into the wood too deeply, leaving deep grooves or marks that are difficult to erase or sand out. This can result in a rough or uneven surface on the timber, affecting the overall finish of the project. Additionally, the hard pencil may be more difficult to erase or remove from the soft timber, leading to visible marks or smudges on the wood.