Theyre needing to put on a roof and the plywood is shot can we add a layer of plywood over the old and reroof?

i know people add double layers of shingles so could we plywood over the old shingle roof without tearing it all down bare. then add a layer of 3 tap shingles i know it is a stupid question but we was trying to find a easier way to do it since we dont have much time thanks for your help