You wanna know what get's my goat?!??

I don't understand why when people call someplace to make a reservation - and the scheduler asks what day/time they would like to reserve - the caller says, "oh let me check my calender, I am not sure when I would like to book." . .. . What thought process did the caller have when picking up the phone to call? "Oh I am going to call and make an appointment - I will figure out when I want to do it while on the phone." That is no good for both parties involved...how annoying.