Indeed  topic positions  must not  be reused  unless you  also reset  the
subscribers' registrations with 'QUIET SET listname TOPICS=-topicname FOR
*@*'. On the other hand, in the  case of a short-lived "task force" style
topic, one  can reasonably expect  subscribers to understand  that topics
are  going  to have  to  be  recycled and  that  they  may end  up  being
subscribed to a  new "task force" discussion if the  list owner forgot to
reset  the subscriptions,  in which  case they  should just  disable that
topic  (they will  already know  the  syntax since  they had  to use  the
command to subscribe to the recycled topic in the first place).
 
  Eric