I have multiple pairs of underwear but I hate h going to a laundromat, so I used to wait until I was absolutely out of everything and the clothes I was wearing were oversoiled.
I have laundry facilities at home now, but when I’m double-plus depressed, I still will wait until I have absolutely nothing to wear.
This was the norm far longer than not. Only nobles rich enough to have washer servants would wear undergarments. The rest of us enjoyed brisk breezes betwixt our nethers.