AdSense must have switched up their ad serving optimization yesterday, because the large 336×280 ad units have been showing 4 ads in an ad unit on most page views, instead of the two ads per ad unit that began showing up under their expanded ad unit optimization.
I did some detailed ad hunting this morning and while I remember seeing all two ads in the large rectangle ad unit yesterday, today I am seeing many more of the four ads in an ad unit, with an occassional ad unit showing two or three ads instead of four.
Many publishers were complaining about the reduced number of ads appearing in the large rectangle, especially because there was no way to force display 4 ads instead of 2. The concern was that there were fewer ads – and thus less choice – for visitors to click on. Others also complained because those using the images beside or above ad units were faced with those images not being lined up correctly to the ads in the ad units.
I am pleased to see the ads are back to four within the large rectangle ad unit. Hopefully this change is permanent, and if not, hopefully they will allow publishers to chose whether they display two, three or four ads within an ad unit.
Forum discussion at WebmasterWorld.