Requested feature overview description.
Set navigation similar to pools, includes basic navigation buttons:

• next,
• prev,
• index (?)

Why would it be useful?
Accessibility/convenience.

There's no other way TMK to navigate sets in a regular browser without manually clicking on thumbnails from the post index.

What part(s) of the site page(s) are affected?

UI: Sets

• */post/index/* [?]
• */post/show/*

requested previously (Nov. 2014):
https://e621.net/forum/show/142381

Also noticed there's a section at the bottom column of the /post/show/ page:

Related Posts
Previous / Random / Next
Sets with this post

maybe something could be done with that too? ->

Related Posts
Previous / Random / Next
Sets with this post
Previous / Random / Next

The thing to note here is that, sets are usually much larger than pools. And unlike pools, sets don't store order of featured posts. Navigating sets should probably be done from "the most recently added to the set" to the "least recently added to the set". But would everyone want to navigate the posts in the set in this way?

titanmelon said:
Also noticed there's a section at the bottom column of the /post/show/ page:

maybe something could be done with that too? ->

What good would that do? The previous/random/next refers to the post ID, where "previous" is N-1 and "Next" is N+1. Random is random.