Optimal area of the paddle to flat hit?

Its wrong to say that for topspin the top-right of the rubber is the best.
In some situations its the best, for others its not. For higher balls the down-middle is better.
And it depends a lot on the distance, the incoming tralectory angles, your position, desired placement.
Anyway using the centre of the sweetspot is always safer.
For flat hits the longer central axis is the best, usually the centre, for paralels its upper side.
 
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