When my 17yo was doing A levels I was working away from home during the week & came home at w/e & did laundry. He was socialising as they do at that age, & wearing own clothes for school & I would have about 20 tops in a pile in his room to be washed. I think he used to try them on, decide "no not that one" & try another & the discards went to be washed.
But once he had to do his own washing, that stopped. It is a generational thing - being working class at Grammar school, I had clean pants every day but blouses, bra & tights were supposed to last a week. My middle-class friends were horrified, but being a "tomboy" type I sided with my mum.
I do find I can only wear tops next to my skin for one day, if I wear them any longer I don't smell fresh, but I do try to minimise the amount of laundry we do, with clean tops for me every day, mainly for environmental reasons.
I would encourage them to do their own laundry but if they can't abide re-wearing clothes, they're probably mainstream these days. It's the downside of laundry being so much easier than in the days of tubs & mangles.