As the old adage goes: "Wash on Monday, iron on Tuesday, mend on Wednesday..." But with modern conveniences like washing machines, is there really a need to have one day set aside for laundry? The truth is that it's actually not a bad idea to keeping up the old "laundry day" routine.
Putting laundry day in your schedule makes it harder to forget, which helps keep dirty clothes from piling up until you're forced to have an emergency all-day laundry marathon. It also lets others in the household know the deadline for having all dirty clothes in the hamper, so you can skip the dirty laundry treasure hunt. And having a weekly washday will keep you from doing laundry more than once a week. It's not very efficient (energy- and labor-wise) to do a bunch of small loads. Clothes actually come cleaner if they're washed in medium or large loads and if articles of different sizes are mixed together.