Pianists in our ranks who have played Olympia's Doll Song from Tales of Hoffmann with coloratura sopranos have realized that midway through the aria the singer winds down and needs to be wound up in order to continue. This requires the pianist to leave their seat, briskly walk up to the soprano, wind them up, and then return to the keyboard in order to resume playing the aria. The YouTube below featuring Sumi Jo and Vincenzo Scalera is a prime example of this technique. Notice how Mr. Scalera uses a prop (a closed fan?) for this duty with great élan.