Our syllabus is a pretty long document, and unless the student is right on the ball it's not easy to get through it in the minimum hours. Having said that, our average is 50 hours but we have the advantage of good weather.
In my experience it is the time to go first solo which makes the hours add up. Often this is due to people being put in the circuit before they have grasped the basics of how to fly the aeroplane, and as a result are behind the aeroplane for the first few hours, instead of spending another hour or two in the training area to get them able to climb, turn, fly straight and level and descend without too much effort before going into the circuit.
You can also save them a lot of time by telling them that if they focus up during landing and not down they will save hundreds of dollars! That sort of motivation works every time. If they get into the habit of looking just over the nose instead of into the distance, it can take many wasted hours just breaking that habit before they can grasp the flare and landing.