Why cleaners work from high to low, dry to wet

Dust falls. If you mop first and dust the shelves afterwards, the floor needs doing again. That is why every visit starts at the top of the room and finishes at the floor.

Dry before wet works the same way: dust and vacuum while everything is dry, then wipe surfaces, then wash the floor last, working towards the door.

Try it at home with one room. It takes less time, not more.