Here’s a list of things I would like to have in Coda in order to save some time while working!
Set a default value for button alerts
.
Set a default value for button size
Duplicate columns please
A page index would be very helpful
Leave your suggestions on the comments!
duplicate column would be my biggest time saver
I feel Page Index as you presented it already exist, as @Johg_Ananda mentioned, its Nav Bar.
I agree with duplicate column, that would be nice 
I have 87 pages in my doc, which makes it very unefficient to have them all visible at all times
I’d like to have an index so I can see an overall view of my doc without having to open every single subpage on the nav bar menu, but I agree that It’s a very specific, and not something as essentialy needed as duplicating columns or default options