If by bathing you mean "fulling immersing yourself in water", then yes, most people would only bathe once a week. Keep in mind that most people did not have running water in their homes until around the mid-19th century so taking a full bath in the past often meant have to haul multiple buckets of water.

That being said, though, it was very common to take sort of sponge baths everyday by washing the face, hands, feet, armpits, and genitals. (I did that recently when our pipes got filled with resin from a malfunctioning water softener and I found that I stayed surprisingly clean even without taking a full shower.) Also, it's important to remember that handwashing before meals was a must throughout pre-modern Asia and Europe.

The real problem was not so much lack of bathing as a difficulty keeping water clean. That had also been a problem in the ancient Roman public baths; the water in them was not chlorinated like modern swimming pools are, which meant so rather than preventing disease, they seem to have been very likely to given visitors internal parasites.