I'm afraid, Caw1, that I can't recall a time when I didn't have at least a couple of books on the go at the same time. I've just "done" this week the Hilary Mantell one you mention, finished that.
Kate Atkinson's latest Jackson Brodie is ready and poised to take over.
I have actually got a book on Ghengis Khan by - I think - Bamber Gascoigne, somewhere downstairs on a bookshelf with other work on similar civilisations, but not re-reading him at present.
In sitting room, re-reading Olivia Manning's "Balkan Trilogy" as a real period piece.
Bedside: Joyce Grenfell's first autobiography.
In the conservatory, a Robert Goddard semi-thriller.
Dining room side table has a book on Venetian Art on the go.
Handbag holds usually a slim paperback, just in case I'm stuck, think ( I haven't looked in there for a while, as can't get out) it's a Scott Fitzgerald one.
There's also a book in my car, can't tell what without going out to look.
In the kitchen, I must admit, the book on the side shelf has been neglected for the very welcome daily crossword that I'm really relying on to keep me sane when not reading.
Not sure all that's any way to ward off dementia, I enjoy re-reading books I've not read for a long time. Sadly, as I've a good memory, thrillers don't work well that way, as I remember the plot too well.
And as design used to be my business, I simply couldn't bear any colouring in book for adults or children! Too boring, I'm afraid, it doesn't help me switch off - although I used often to do the drawings for children to colour in, when needed.