I find out kind of odd, I’ve almost always read on a tablet in landscape if I was reading for a prolonged period. Yet settling in for an afternoon of reading, I find self happiest in landscape.

Wide screen 10” form factor has never been my bag. The 16:10 typically found is just crap in portrait, and out approximates a form that was really meant for landscape video. Now the 7” and 8” tablets I’ve owned were different stories: despite the meh aspect ratio they’re usually sizes on par with a paperback. In fact I’d say the old “Thor” model HDX 7 was about the perfect size for reading.
Standard 9.7” on the other hand is like the perfect all purpose form factor, thanks to the greater squareness of the 4:3 aspect. Thus I’d still read novels in portrait mode and do everything else in landscape or portrait as I prefer.
The standard 11” of the iPad Pro, I’m finding it easier to focus on reading in landscape mode. Conveniently it creates a very book like pages side by side effect on the perspective. Much like how you might focus on an open book.
Kinda odd to me because of how similar the sizes are. Nerine’s screen is the size of Scarlett; such that if you just put bezels around the Tab S3 and make the screen that much bigger, you’ve essentially got the iPad Pro 11 right there. That is to say, it’s what happens if you take the most perfect multi purpose  size and blow it up about as big as you can make a tablet that’s going to be used often with one hand but most frequently with two hands.
Anyhow, back to my book 😜.