Summer humidity slows the air drying process, too, if you intend to hand wash anything. A powered hand fan which is useful during the summer can also be propped up to help circulate air for air drying clothing.

Some business hotels have all in one washer and dryer machines which can inspire love hate relationships. Love for the convenience, hate for the dryer taking so long and often leaving things slightly damp. Perhaps it is the amount of clothing travelers save up for a load or a condensing dryer. It was unpleasant for my friend on our trip who was confronted by a pair of waiting hotel guests when she attempted to add some time to her "completed" very damp laundry load that she'd "had her turn" in the evening (note - I don't think most Japanese manners would consider it unbearably rude to add a single time extension if using 1 of 3 machines with dryer time added right as the initial cycle ended, though perhaps someone else's culture or ahem, certain personality types might. Annoying but understandable for regular clothing). Laundromats or places with a separate dryer like Dormy Inns are more efficient, or hotels with washer/dryer unit in room so you can throw in a load at night (estimate 3+ hours for wash + dry of a single load). I'd expect outsourced hotel laundry service to be fine.