This is a question that we often get from sitter and owners who work with Rover. Help the community out by answering them in our forum!
Wash your dog when he is dirty or develops a doggie odor. If you use a high-quality shampoo, then you will not need to worry about stripping the oils and causing skin irritation.
I use a tearless puppy shampoo and since my dog sleeps with me I bathe him 3 times a month. I have done this with all my previous dogs and have never had any skin issues.
Dogs with normal skin typically should be bathed once a month with a decent quality shampoo. They have some great dog shampoos on the market for all coat lengths and many different skin types. If your dog's skin has issues, you may want to try a sensitive skin shampoo and talk to your vet as you may need to bathe dogs that have allergies or certain types of skin issues more often. A good brushing between baths along with fish oil supplements and/or pumpkin can help your dog's coat stay shiny and healthy :)
What breed is your dog?