Loads of people do this as they can make a lot more charging per hour as they can per day.
£70 a day is around average or say someone doing three hours at £40 or £50 an hour. However they do tend to have a high influx of girls coming and going so all the neighbours will be aware what is going on
One of the girls I know works at one of these type places twice a week and there are dozens of girls working there throughout a week as each room is rented per hour (normally three as they rent a single room as well) so on average 2 to 4 girls per day in each room.
No good for an outcall though as the majority who rent these places out are men who only rent to females