Unfortunately, for this section, the author relies exclusively on the example of the Indre-et-Loire, department in which access to such records is particularly easy, since everything is deposited in the departmental archives. In the department where I do research, many documents have remained at the mortgage office and research are much more difficult. They require back and forth between the office (fee) mortgages and archives (hopefully free). Which is not shown in the paper.
However, it seems that my department rather be part of resorption lane exceptions. And that the "normal" situation and soon general is that of the Indre-et-Loire. The book should therefore be applied to an increasing proportion of the departments.