off the hip

impromptu spontaneous

by-the-way extemporary extempore improvised informal off the cuff off the top of head spur-of-the-moment throwaway unpremeditated unprepared unrehearsed unstudied without preparation

calculated careful considered deliberate planned practiced

abrupt breakneck brief frantic gone off half-cocked harum-scarum hasty headlong heedless hurried ill-advised impatient impetuous indiscreet jump the gun madcap off the top of head plunging precipitant quick rapid rash reckless refractory rushing subitaneous swift unanticipated uncontrolled unexpected unforeseen violent willful without warning

careful cautious slow

ad-lib by ear extemporaneously impromptu improv improvised makeshift off the top of one's head offhand unrehearsed