For the period from the exodus to the exile genealogies vary greatly. Some are in great detail, some are sketchy. Some purport to give a full chain, though these are sometimes suspect. Many make no attempt to do this, but list a series of names, often called sons of a person, but then it says these are the heads of their households.Gaps in the chains
In other places, while giving lists of the children of one of the tribes, a name is introduced as father of a series of children and maybe even a chain of descendants without any attempt to link that name back to the father of the tribe. When I have met one of these cases I have created an entry called "desc. of . . ." (Short for descendant of . . .) and given the name of the ancestor who is known before the gap. The historical positioning of this chain may sometimes be done by a reference to the person involved, but is often uncertain, unless the text gives detail, as in the case when it states that a certain person was taken to Babylon.
An example of gaps in a chain is illustrated by comparing Ruth 4:18-22 with 1 Chron 6:22-28 and 33-38. In the Ruth reference there is a chain of ten generations from Judah to David. In the Chronicles reference which deals with the tribe of Levi there are twenty-one generations listed from Levi to Heman, who was a temple singer in the days of David. It is unlikely that there would be that much difference in the average length from birth to the son who continued the chain in the two tribes.Differences in the lists
Another cause of conflict that is not so apparent until lists are compared can be illustrated by the children of Benjamin.
Gen 46:21 (NRSV) The children of Benjamin: Bela, Becher, Ashbel, Gera, Naaman, Ehi, Rosh, Muppim, Huppim, and Ard
Num 26:38 (NRSV) The descendants of Benjamin by their clans: of Bela, the clan of the Belaites; of Ashbel, the clan of the Ashbelites; of Ahiram, the clan of the Ahiramites; 39 of Shephupham, the clan of the Shuphamites; of Hupham, the clan of the Huphamites. 40 And the sons of Bela were Ard and Naaman: of Ard, the clan of the Ardites; of Naaman, the clan of the Naamites.
1 Chr 7:6 (NRSV) The sons of Benjamin: Bela, Becher, and Jediael, three. 7 The sons of Bela: Ezbon, Uzzi, Uzziel, Jerimoth, and Iri, five, . . . 8 The sons of Becher: Zemirah, Joash, Eliezer, Elioenai, Omri, Jeremoth, Abijah, Anathoth, and Alemeth.
1 Chr 8:1 (NRSV) Benjamin became the father of Bela his firstborn, Ashbel the second, Aharah the third, 2 Nohah the fourth, and Rapha the fifth. 3 And Bela had sons: Addar, Gera, Abihud, 4 Abishua, Naaman, Ahoah, 5 Gera, Shephuphan, and Huram.
After reading these four references, how many children did Benjamin have? How many in one list are shown as grand-children in another?
I do not think this is necessarily a case of inaccuracies. I think the various recorders were interested in different aspects. The recorder of Genesis was interested in the children of Benjamin in the sense of the descendants (just as the tribes in the wilderness and later are usually called the children of Israel). The recorder of the book of Numbers was interested in the clans of Benjamin, whether the persons after whom the clans were named was a son or a grandson was immaterial, they were all clans of the tribe of Benjamin. The writer of Chronicles is after more accuracy probably but maybe working from different, and incomplete, sources in the two chapters.