I had been wondering lately if we needed a different way to quantify the length of a book given the variability of the digital experience.
There is no way really to tell how long a book is going to be when you download it electronically. Weight and thickness have disappeared. The screens you read on are smartphone small to desktop big.
And it struck me: time is the standard for digital products.
I wrote a whole essay on the subject for Publishing Perspectives, which they posted today.