Sometimes. Our recommended installation for best performance where nails and glue can hold is to go over plywood or OSB. If it is a remodel and you don't want to install plywood because of hassle or defeat the benefit of thin wood wall paneling then ideally paint light colored sheetrock a dark color and use polyurethane construction adhesive to attach the wood planks to the drywall. One is more likely to have problems when installing over sheetrock instead of plywood.