Stig, the original request was that the lisp that WB had would not retrieve the last number used, we were simply trying to fix an otherwise fine lisp by having it retrieve and store the last number used.
There are merits to any system used, but no matter how you look at it, somewhere someone MUST run a lisp, vba or macro and since the lisp is what will number the duct pieces, the user cannot simply "forget" to run it, to do so would be to "forget" to do their job in the first place.
I know there were at least 5 good solutions to this scenario the job of deciding which to use is up to WB, that is why we have a forum to get everyones input.