To be fair to France, I think this is quite clever for their nomination,
It certainly plays a major role, how such serial nominations can be managed. Particularly for industrial regions it is necessary to allow further development and to meet the requirements of the Unesco. There are several examples for such conflicts. To define more sites and smaller buffer zones could be a clever strategy. And the acceptance in the population is higher if every town can include some objects.
However, to include 124 workers' estates and social habitats, 26 religious buildings and (under the item 'other facilities') a signalling box sounds strange.
Good examples for different strategies are the efforts in Germany to nominate their industrial heritage
The nomination of the Erzgebirge mining region (transnational nominatiion is expected for 2015) shows a trend similar to the French approach: there are almost 60 sites on the list.
A different example: The Ruhr is working on an extension of the WHS Zollverein for the new German tentative list. The previous list includes only about 20 objects. The strategy is to select exceptional sites representing the different aspects of mining.