Aside from fitting the window size (as described above)
You may wish to consider what you are displaying, why and to whom. And whether having 24 pie charts in a single sheet is optimal for your audience.
I would ask yourself - is it easy to read? Can my audience draw conclusions from it?
There maybe better ways to display... either without using pie charts or at least bring the volume of charts down so its a little easier to read.
Couple of interesting blogs for ideas -
Best of luck!
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