Biannual laundry might be taking it too far! Jeans don’t need washing every day, and I will often use the same ones for a couple of weeks, especially while WFH. But after a couple of weeks you might notice a bit of odor if you bring them close(ok most people won’t get close enough to smell your jeans). And they will noticeably loosen, wrinkle, and lose the more form fitting shape they have after a hot wash/dry.
Another factor that may not be as relevant when working from home* is that general dust and dirt settles in and between the cotton fibers and act as abrasives. You can get a lot of that out by giving your jeans a vigorous shake out the window, but cotton is very absorbent and will hold on to dirt and grime, so it's a losing battle. If you never wash them, the wear will accelerate and ruin the fabric, especially in folds and creases.
As an aside, some of the "common knowledge" around jeans actually does apply to wool clothes since unlike cotton, the wool fibers have a hydrophobic outer layer, so they will repel dirt. Hanging wool clothes overnight and giving them a shake the next morning is often more than enough to refresh them, cabin luggage-only travelers love merino wool t-shirts for this reason, they can be worn for several days before needing a wash, without developing odors.
* Are people wearing jeans when working from home? As long as I'm staying inside, I'm wearing comfy cotton pajama pants and a hoodie or a robe all day, it's so comfortable. The real pants or jeans are only worn for going outside.
Yes. All of my jeans are part elastane and are very comfy.
But none those are even close to being as comfortable as pajama pants or sweatpants. When I'm lounging at home, I want nothing to bind or sit tightly, comfort is king.
Wearing a belt while sitting down puts a lot of pressure on your midsection, but even wearing suspenders (which I highly recommend), you still feel the waistband. Of course you get used to it, but why not just go straight for comfort?