I've read two books by Tamara McKinley lately. Her pattern seems to be - start by telling about one set of characters, get them to a crisis point and then start a new chapter and a new set of characters.
In Windflowers there is also a time shift. A scene break may shift characters forty years forward or back in the story, which had a "secret" and I must admit it kept me reading to the end to discover the "secret." The story line must have been very hard to control for the author. I can only imagine she had a really strong chapter breakdown ready plotted before she began the real work, and wrote the story from that. Otherwise, the opportunities for confusion seemed endless!
I romped through Amanda Grange's Captain Wentworth's Diary a few days ago. Excellent book!
I don't know if Mandy visualised her particular Captain W as she wrote it, but for me Rupert Penry-Jones waltzed in and took over the character lock stock and barrel. It turned out to be another example of a first person narrative where I barely noticed the single POV.
The pic is the Roman altar stone in Halton churchyard.