I love publishing collections because the material already exists, it’s just a matter of putting it into a new package. And since some people prefer a collection over individual titles (especially on the fiction side where it’s usually called a box set even in ebook format) it reaches a new potential audience.
So, having said that…I just published the collections for the Affinity Publisher titles. The first, book formatting, combines fiction layouts and non-fiction into one title. The second, ads and covers, combines ad creatives and basic book covers.
And I published my first bright yellow cover, which was fun, too. In ebook there’s no price difference between buying the titles separate or buying the collection, but buying the print collection does add up to some savings.