It would work, but areas (the pattern) wouldn't join smoothly :(( There
is
unfortunately no better solution now.
At the scrap joins, you should try to avoid any symbols. If there are some, usually -clip off helps (if you do not need to clip them by scrap border). But in the case of area that exists between walls, it would probably not help.
OK - this is a real problem for a cave containing a long streamway. There is a very long continuous 'water' area. This connot always be drawn as one scrap. As you say the pattern rather obviously doesn't match up at the join. I think we need to have some mechanism for making such smooth area joins in the medium term.
I have tried this now and it works :-) It seemes that PDF viewers optimize filling of adjacent areas and join patterns smoothly. Martin