Between the 2 of us, probably less than a load per week. I'm a bit surprised at some of the high frequencies on the thread. I get if you have kids that have accidents your usage would go up. But things don't need to be washed all the time, and you can fit a lot into a load.
So much of this is lifestyle specific.
DH's job involves meeting with business people alternated with repairs that can be quite dirty. He changes shirts between duties, the dress shirt can last a day or two but he might go through 3 grubby tees in a day. Jean's can often go two days but not always.
We live far out in the country on a working farm. Beyond the poop hazards that Erica mentioned, I'm often sweaty and working with dirt, mud, machinery, and itchy things like hay and grains.
My day job is business casual - those can go several wears between washes.
Bath towels and sheets can go months, but we use tons of hand towels and rags.
2 people, 5 loads a week.
That. Basically.
My husband and I both work office jobs (business casual: shirts and underthings get washed after a full day of wear, pants get re-worn. Similar to what most people on this thread do.) But then we get home and switch to work gear and deal with the toddler, the barnyard chores, and the general outdoor chores (change #2 of clothes in the day). And then, once the work is done and the kid is in bed, we take a shower and slip into flannel PJ pants or sweats to curl up and read/watch TV for a half-hour before going to bed (change #3 of clothes in the day). And that's not even accounting for the toddler getting into the finger paint (or, when she was younger, puking up on everything that stayed still long enough).
Look: PJ pants get re-worn for most of the week, business wear gets washed when it needs it, farm gear gets washed every two days or so and kept in the machinery room (no way is there chicken poo in my bedroom, not happening)... but with our lifestyle, I can't really see of a way to do less laundry.
As Erica said: could we do better? Possibly, but not without significant effort/sacrifice, and I think there are much better places for us to be putting that energy (places that will save more money, as a starting point). So... not my frugality hill to die on. (Home cooking, minor animal-keeping, the aquaponics set-up I want to start in the spring, no take-out lunches, tailoring and fixing of clothing instead of buying new, limits on electronic gadgets, being a 1-car family and limiting car use... yes. Laundry: high effort, low returns.)