I've done laundry a few times on cruises and I'm sure at least once on the Glory, I never found it crowded. But if it is do your laundry on a port day when others are out spending money on shore.
Or if you have a balcony cabin bring a looooong rope and a mesh bag, if you get my meaning
Or if money is no object you can have valet service do it. About mid cruise an order form will show up in your cabin. A dollar for a pair of socks, $2 for briefs and 2 bits for tighty whities, something like that