If they say this to me I just say it will be for one hour maximum as I don't do longer than an hour with new clients.This normally takes the wind out of their sails.I find it a vaguely rude way of hinting that they may wish to extend and it is almost like they think I will make extra effort to secure an extension from them which won't be happening,they get the same service as anyone else.From a business point of view then obviously you need to know how long they are booking for so you know what time to book other clients in afterwards.I generally find guys that use this phrase are often dicks or timewasters or when it comes to it they pop in 2 mins and can't go again and for sure can't extend anyway.Genuine guys usually just book for a set time and if they happen to want to extend they will ask if this is possible during the actual booking.
we are trying to run a business here and don't have all day on the offchance for their whims and preferences. Time is money. It just doesn't dawn on plenty of clients does it!!
I always say I need the be able to plan my day so I need to know either way or I can't take the booking. This pisses me off too MS, I used to take it too personally and I'd just get upset! I used to say I'm not desperate enough to over work myself. I work for my money but I dont need to stress thinking I need to be good enough for the possibility of more money, I'm better than that!