off the top of head

ad hoc ad lib at first glance automatic by ear casual expedient extempore free immediate impromptu improv improvisatory improviso informal jamming made-up makeshift off the cuff offhand on impulse on-the-spot snap spontaneous spur-of-the-moment taking for ride thought out loud tossed off tossed out unplanned unpremeditated unprepared unstudied winging it

planned prepared read rehearsed written

impromptu spontaneous

by-the-way extemporary extempore improvised informal off the cuff off the hip 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 hip plunging precipitant quick rapid rash reckless refractory rushing subitaneous swift unanticipated uncontrolled unexpected unforeseen violent willful without warning

careful cautious slow