That is a great question, and the reason why bookcases come with variable shelves.
And you can have custom-made bookshelves built with this feature
(which may be easier and cheaper for the carpenter than mortizing
fixed shelves).
It is also a matter of space. If you have lots of it, you can be
generous and put smaller books on shelves that could take larger ones.
It also depends on your sense of order: if you want your books all
sort by topic, you're going to have to allow for large and small ones
on the same shelf, which uses up space that could be save by sorting
the books all by height (which is a good way to lose track of them :),
as I know).
"The average home"? See my first sentence. If you collect art books,
you're probably going to need more higher shelf space than the average
home. If you don't throw away paperbacks (at least they are pretty
uniform in height), you can plan for that.
I had a bookshelf with fixed shelves made, knowing what was going to
be shelved, and ended up with one very low shelf that I was going to
put little brick-a-brack on, but it turned out to be just the right
height for a set of Shakespeare!
In the end, years from now, it won't have been entirely right. Look
at the shelves behind persons interviewed on TV: double rows on a
shelf, books lying flat - on a shelf or on top of other books, ... |
