Bathing a dog once per week can be done if the dog is dirty and needs a bath once per week.
But bathing the dog once per week can actually dry out the dogs skin so I would not recommend it.
Unless the dog gets dirty or muddy etc then giving the dog a bath once per month is good enough and will keep their fur and skin healthy.
If you do need to bathe your dog more than once per month you should use some moisturizing dog shampoo to keep the skin from drying out.
Do not bathe your dog more than once per week though because bathing the dog more than once per week can really dry out their skin.
So just bathe them once per week if needed or once per month if they don't need bathed once per week.