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Yes, but they warm up every day and keep their skills honed. And the reed players spend many hours making reeds. edit: there are also many hours of score study and listening to recordings involved. And there are often 3 or more concert sets of different music to learn each week.

Young musicians and professionals often practice in excess of eight hours per day if/until they win an audition for a group that has enough salary to sustain them.

Most professional orchestras rehearse 3-4 times for what's usually called a "Masterworks" ie the usual subscription concerts. Only something like a pops or light classics concert will be one rehearsal and a show.