It is not the practice of the Hebraica Team to create NARs for 130s that do not have references, unless there is need to show special data derived from researching the heading.

As for the 100/240 combinations where the 240 differs only from the 245$a because of the lack of initial "Sefer," this
practice is documented in HMC, p. 46.  As one can see from a careful reading of this passage, whenever a 245$a begins with "Sefer," the cataloger is technically required to make sure that the author of the work has not written any books in the catalog with titles NOT beginning with "Sefer."  If he HAS written titles that don't start with "Sefer," a NAR is required for the one that DOES.  This practice is a special dispensation for the Hebraica Team, because without it we'd have to make so many (rather unhelpful) NARs.

As for the 100/240 combinations where the presence or absence of "Sefer" is not a factor, the lack of a NAR is probably a
mistake, and  LC will check them out on an as-encountered basis.