without preparation

impromptu spontaneous

by-the-way extemporary extempore improvised informal off the cuff off the hip off the top of head spur-of-the-moment throwaway unpremeditated unprepared unrehearsed unstudied

calculated careful considered deliberate planned practiced

impromptu

extemporaneously extempore off the cuff off the top of one's head spontaneously without rehearsal

deliberately planned prepared rehearsed written