Recently our section traffic manager w3yvqhas been showing us a new technique which is used on phone but is  similar to the qsk method we use on cw.  Before I begin a message or series of message such as a book I tell the receiving station that I'm listening between groups.  If the receiving station needs fills all he has to do is say the last work he copied completely.  This is also helpful when conditions have been marginal like they've been lately.  73- pat kk3f