The submitted lineages have errors because they were submitted by people (not always Mormoms) who didn't know what they were doing (the same goes with the Ancestry lineages). However the records in the form of microfilms and transcribed databases of church registries, censuses, military enlistment documents etc. etc., are 99.99% accurate. It is the compilation in one place of all these records that is so valuable. The lineages are still useful for pointing you in one direction. If you see one that says you are descended from Ben Franklin, that's nice, but you need to verify the sources that person used yourself. Genealogy is long hard work, but it's very rewarding when you know the details you found are thorough and correct.
That all said, I am confident that these Presidential lineages are accurate. When the Mormons release this stuff the last thing they need to is to reproduce some goof a little old lady made 50 years ago, so they have professional researchers sit down and reconstruct the entire thing record-by-record.
I found errors even in the microfilms, not just submissions. Even my genealogy instructor at BYU admitted the records aren’t as accurate as they claim.
just sayin’ my experience is different and I never trust anything that comes out of Mormon HQ - again based upon experience.
That should have been errors in the transcription of microfilms.
When I work on geneology, I get the records directly from the county/town/ etc, never through Ancestry.com.