Yes, well, if you find yourself cross-posting things over an extended
period of time, as opposed to an occasional discussion on a particular
topic, there is clearly something wrong. Since your topic is relevant to
multiple lists it is likely that many people will be subscribed to more
than one of these lists and they probably aren't looking forward to
multiple copies of a discussion over an extended period of time. So the
best thing to do is select a list to hold that discussion and invite
people who are interested to join it.
Eric