Pretty common in dryers as well.

They turn over and blow cold air periodically to prevent them getting stinky.

but why???? If i have already gotten off my ass to go throw the clothes in it and so I'm literally standing right next to it, in what universe won't I just press "start" and instead press a bunch of buttons to set up a timer?

If you want to run it overnight, or while you're at work, so it finishes as you arrive and doesn't leave the clean clothes in a clump for hours (or so it runs during cheaper power hours)

Yep that.

30p/kWh in the day, 12p/kWh at night.

Dry an entire load for less than the cost of a Day Rate kWh, simply by pressing the "delay" button a few times.

>and doesn't leave the clean clothes in a clump for hours

As opposed to having your clothes be in a wet clump for hours? Between the two choices I'd prefer it being dry, because I know at least there will be less microbial activity.

In Japan, most regions have cheaper electricity at night, sometimes at up to 50-60% discounts. That might be a factor as well.

It’s not common to have separate units here though. Much easier to setup a wash/dry cycle timer.

They also sell combo units (mostly for small apartments), so you don't actually have to move the clothes to one from the other