I will have to support Paddy because it is NOT about the length of time you make your show. It is the material that you provide and the amount of the time you are able to provide it in depends on how GREAT your show really is. If it takes a movie two whole hours to finally interest you, that is not a great movie. If it takes a movie 15 minutes to dazzle you, incite interest, and make you constantly wanting for more, that is a great movie.
Magic shows are exactly the same way. Anyone can buy a shopping cart full of tricks and show them one by one, giving each their own allotted time. No touch of identity or personality. Just tricks, with props that have no quality of magic, and instructions printed over a thousand times. That is what children will see if you dare to go up to a stage and perform endless trick after trick for such a long time. They will get bored, they will get anxious, they will boo you off the stage, turn away and chatter, and you will fall apart under the weight of all the tricks that you uphold with so little value.
If you want to do tricks to waste time, then that is exactly what you are doing to the spectators, the audience. You are wasting their time. You are not entertaining, you are merely an advertisement, a poster board displaying something that the audience can only visualize, but not feel nor interact with. So if you want to create a show, a magical show, a show that has its core in the heart of entertainment, then you will certainly add quality to your "tricks", add a routine to your performance, and create a patter that is thrilling and compelling.
So, I agree wholeheartedly with Paddy, when he says reduce the time, and reduce the "tricks". Instead, create a true magical show, consisting of practiced, polished, original routines that can truly restore the reputation of magic, that this art truly needs.
As Paddy always said, "Always leave your audience wanting for more." A 45 minute show with trick after endless trick will not give them that. It'll leave them with a thought of wanting you off that stage so they can get on with their lives.
I apologize if I sound spiteful and angry, I am just very passionate about performing, especially for children and families. I would not want anyone to be offended by what I have to say, I am just giving an opinion that has been developed through experience, and wonderful advice by the experienced magicians that have aided me. I hope you take the same road, and accept the advice that these people who have made their lives on the art of magic, pass on to you.