
Vertical Scrolling — This is how to improve user experience of book reading.
When I start working for a friend’s app for Urdu book reading, I decided to follow one simple formula of instead of “side-by-side sliding” for pages in the book in that app. I decided to follow the standard convention, which we adopted for web pages since the birth of internet which is “vertical scrolling”.
Here is the screenshot of that Urdu book reading app:

Also, BBC GEL “How to design for touch” recommend the same interaction. It reads:
Scrolling
On touch devices, vertical scrolling feels natural and is less effort than tapping. Scrolling is also more accurate on devices, with better control over speed and position. Where appropriate, think about exposing content to favour a longer scroll instead of excessive tap actions. Where tap interactions are needed, maximise the size of targets that are likely to be used again and again (like slideshow controls). Scrolling elements should support native (inertia) scrolling to make it more realistic, like the ability to ‘flick’ and ‘bounce’ at the end of a scroll.
source: https://www.bbc.co.uk/gel/guidelines/how-to-design-for-touch
Today when I open the Amazon Kindle app on my iPhone I noticed that they introduced the similar interaction for book reading. Which I believe will speed-up the reading experience.

This article is just a pat on my back that I adopted this interaction design for the Urdu book reading experience little earlier than the giant Amazon (another 1 trillion dollar company).