I think this is the most efficiency of split layout:
Left 1 , Right 4 square .
If more than 6 , 7 pages, you even can’t edit any page. bcz they’re very small.
Althought currently doesn’t support multi-tabs, but 5 pages like that layout is quite enough and the most efficiency by my experience.
If support multi-tabs, you open 10 - 20 pages, the performance of software is the problem.
So keep simple, 5 page like that layout is quite enough.