Doesn't work too well with paper sources. It is
unreasonable to expect
people to spend large amount of time in a libiary before deciding
which bits are and which bits are not sourced particularly if the
article is expanded in more than one go or I decide to expand the
[[Salisbury and Southampton Canal]] article using Edwin Welch's "The
Bankrupt Canal"
There is no way for them to know what bits are sourced correctly
without going and finding the source, whether it's cited a dozen times
or once. As I've said, incorrectly sourced is far worse than
unsourced.