Turns out, I used to wash my jeans too often. A spokeswoman from Levis answering this question on quora wrote:
We suggest washing every five to six wears. Although there are some that advocate washing as little as possible. In fact, the director of brand concepts and special projects […] washes his once every six months.
The general tone was that you should wash them as seldom as possible. That’s not only better for your jeans, but also for the environment. To break down odor or bacteria, you could put them in the freezer instead.