Google just made a policy change that is bound to make web publishers happy — they often don’t make announcements about product and policy changes and users are left to their own devices to eventually figure it out.
This is the reason why there are hundreds of web publications dedicated to documenting changes and updates to Google search and ad products. Most of these publications depend on lucky breaks — accidental discoveries, word sent in by insiders, and tips by users.
We recently found out about an important policy update in Google AdSense via one of the aforementioned means; these are important changes, and as far as we can tell, no one has or is covering them.

Visual Proof of Policy Change

You can view the exact changes that have been made to the ad serving policies by clicking on the two images below; the older image is a screenshot from 10/08/2016 and the other image contains the new policy.

Detailed Account of Policy Change

Here are the text excerpts of the old policy, which has now been removed, and the new policy that has been introduced in its place.

> Old (obsolete) policy: Ad limit per page

Currently, on each page AdSense publishers may place:
  • Up to three AdSense for content units
  • Up to three link units
  • Up to two search boxes
Publishers may not place more than one “large” ad unit per page. We define a “large” ad unit as any unit similar in size to our 300×600 format.
Go here to read the full text on Wayback Machine.

> New policy: Valuable inventory

Advertising and other paid promotional material added to your pages should not exceed your content.
Furthermore, the content you provide should add value and be the focal point for users visiting your page.
For this reason, we may limit or disable ad serving on pages with little to no value and/or excessive advertising until changes are made. Examples of unacceptable pages include but are not limited to:
  • Mirroring, framing, scraping or rewriting of content from other sources without adding value;
  • Pages with more advertising than publisher-provided content;
  • Automatically generated content without manual review or curation;
  • Hosted ad pages or pages without content;
  • Pages that don’t follow our Webmaster Quality Guidelines.
Source page for new policy.

Summary of Policy Changes

  1. You can now place more than 3 ad units on a web page.
  2. You can now place more than one large (> 300×600) ad unit on a web page.
  3. Policies still only allows one 320×100 ad unit above the fold on mobile. Below the fold, however,  there is no limit now.

What This Means for You

Generally speaking, this is a relaxation of policies. If you’ve ever used AdX, you’d know that one of the selling points for its use tends to be about how you can place more than 3 ad units on a page — well, now you can do it with AdSense as well.
The new policy seems to be more about subjective evaluation of content dubbed “valuable inventory” and its usefulness to users instead of a having rigid set of rules to abide by.
It’s not hard to speculate why Google would make such a move — publishers have been having a hard enough time as it is dealing with ad blockers and falling revenues, and these particular set of policies were at the top of the list of reasons that led to account suspensions.