A dog really only needs bathed at least once every three months which is good enough unless the dog has fleas and needs a flea bath more often then once per week would be a good idea to rid the dog of fleas.
Or if your dog gets into a lot of mud or dirt then wash the dog as needed but for general bathing dogs only need bathed every 3 months which is good enough.
Bathing a dog too much can dry out their skin.