It is good manners and good professional practice to give a musician the option of having time to prepare a piece of music if they need or want it. If you want to do something without preparation, try saying something like “I want to do a piece of repertoire from the ballet X – do you know it, or shall we do it next week?”. Don’t assume that because the pianist ‘always seems to cope’ that they are capable of doing everything with no preparation at all, or enjoy living on the edge all the time!
