Jesus, no wonder there's an eco-crisis!
I wash jeans every 5 or 6 washes, I think. Basically when the knees go baggy. I don't wear them every day though so they might keep going for weeks. Obviously if they're noticably grubby I'll wash them sooner. Tops like thermal vests and t-shirts and tunic tops probably wash after 1 or 2 washes - sadly, as I get more perimenopausal, my sweat stinks by the end of the day. I use Mitchum deodorant and people assure me I don't smell, but finding I can't really wear skin-hugging tops more than once or twice.
Dresses, which I mostly wear, I'll wash if dirty or they're armpit-hugging. In winter I wear dresses with long-sleeved thermal tops underneath so I won't wash the dress after just one wear.
Jumpers and cardis (only wool) I will wash when they're dirty or if I can detect an odour. Woollens really don't need washing that frequently as they shed odours and light dirt, and since I hand-wash all woollens I try to avoid it too often!
Underwear obviously I wash after one wear apart from bras and tights. I'm one of the Filthy Unwashed Bra brigade!
But if it whiffs I wash. PJs now I wash the tops after one wear because like I say, perimenopause is kicking my ass and I frequently wake up soaked in sweat.
Don't any of you worry about electricity/water bills, microplastics shed into water, detergent use, etc?? Not to mention the vast time it takes to do laundry if you're washing everything every wear.