Also keep in mind Heather Cox Richardson earned your trust so it's ok to not be as skeptical.
And here's a fun thing: Richardson's most recent books are not presenting new research. They're essentially opinion books based on her encyclopedic knowledge.
I own ALL of her books. I use her as an example because I love her and I'm saying, yes, still question her non up books more.
btw those books aren't formally peer reviewed... But she does have them informally peer reviewed. 3/3.