This is how I do it!
I don't mind... my "justification" (to myself) is that I don't reflect on memories in chronological order, so why should my book have to be?
I'm not motivated to scrapbook chronologically, and I'm highly motivated by printing books, so... printing "mixed memories" books is what works for me. So, when I have "enough" pages for a book (I aim for 100-120) I print those pages. (Project Life are separate and don't count to the 100 & I have a Disney book in the works that will be its own book)
In the last book I printed, the pages in the book are not chronological-- I tried to make colors look nice together on facing pages and was also mindful to have an even distribution of my kids. So I kind of went "page with just son, page with both or everyone, page with just daughter, page with both or everyone, repeat"
My son is 3 on one page, 7 on the next, and 2 a few pages later and it doesn't bother me (and nobody who has looked at my book has been confused by the "time travel"
). I'm just happy to have something to hold & look at.
The next time I print a book, I might do chronological within that book (mostly just because it will be faster as my file names are YYYY-MM-DD Title).
I print on the spine: "Mixed Memories: Vol. 1. 2010-2019" So there's a slight (ever-so-slight, hahaha) narrowing-down of what you'll find in the book. The cover is (got this idea from someone here!) a page from the book without the picture/journaling, so they're easily distinguishable from one another.