While I try to have a laundry closet in each apartment, that may not be possible. Even if it is, there might come a time when you might need a double load machine such as for a very heavy blanket. In these regards, you would be able to use the laundry room to wash and dry your double load items. Some laundry rooms will have seating so you can supervise your laundry. Others may not. If this is the case, you would be responsible to time your return for when the machines are about to finish.
Single load machines are $2.50 per load. The dryer will run for 60 minutes. For double load machines, the cost is $4.00, and again, the dryer runs 60 minutes. If you use multiple machines from 12AM-11:59PM, your charges will be consolidated, and you would be given a final single charge rather than multiple smaller charges. This is intended to reduce the number of actual transactions, and to reduce the budgeting work for your card.