I have a dog - Rocky. He's not a pure breed, but he looks like a german sheep dog. Anyway, I bath him approx. every 6 weeks. By that I mean a "full bath", 'cause he's got long, dense fur and I have to clean him almost every week, especially in the rainy seasons. I use a nettle based shampoo - it's cheaper and his fur gets really shiny. A vet recommended it.
I have a miniature dachshund. They are low dander dogs so I only bath him about twice a year. He doesn't get that dirty dog smell. If you bath a dog too often it dries out their skin. They don't have the same oil naturally secreted as humans.
I do wash his face more often because he has an eye that sometimes weeps due to allergies.
We bathe our dogs once a month or so (unless they get especially dirty in rainy weather). They are outside dogs during the day and they come in at night. They don't have fleas or ticks, so they don't require extra care. Also, if we take special trips out on the boat, they get into the saltwater and they get a bath when they get home.
When my dogs were inside animals they were bathed about every two weeks. They generally played hard enough when they were outside to need a bath at least this often if not sooner. Now that all four of them live outside they only receive a bath every 4 or 5 months. They actually do a really good job of making sure they clean themselves up. (Usually in a mud puddle but at least they are trying.) I will most likely change this to every three months as their new flea stuff is rated at three months so I can bathe them when I give them their dose of meds.
I have two cats and a ferret. When my cat escape we had to give him a bath. That was a nearly deadly experience. My ferret generally has a musky smell so he gets a bath once a week. He doesn't like it, but he is small and can't fight much. If we don't give him a bath, he will start to smell strongly of ferret musk even though he is descented.
My 2 dogs generally get bathed in summer every 6 weeks (or should be) but unfortunately the older dog just jumps into streams and rivers whenever she gets the chance,so therefore every time she does this, we hose her down and shampoo her.
Either she genuinely likes being in dirty water, or she is guaranteeing to get a pampering I can't decide which!