Two Ads instead of 4

Large Rectangle

[Conard]

I looked at a site yesterday that has the large rectangle 336x280 running on several pages.
Instead of the normal 4 ads it had 2.
Then I checked one of my sites and the same thing was being displayed.
Today the same thing is being displayed on several sites I've checked.
Is this a planned change on Googles part or a glitch?

[level80]

It occurs on other sites too. It's planned. It would only show two ads if:-

there wasn't enough ad inventory to fill it (eg you say have another 10 Google ads already on the page)
if two larger ads will net you (and Google) more than the four

That's my take on it anyway.

[Conard]

Strange plan as one of the sites I checked that displayed 2 ads has the same topic as another site that uses a different 4 ad format and all four ads show.
To test this I changed the layout to another 4 ad layout on my site and all four show. Changing back to the original layout and only 2 ads show again. These pages only have one ad layout each so I know there is enough inventory.

[bether2]

FYI, this is being discussed over here:

[webmasterworld.com...]