netmeg - 3:26 am on May 29, 2012 (gmt 0)
The recommendations in your account are generic and sent to everyone. They aren't necessarily the best advice for everyone.
Now, if an AdSense rep actually contacts you via email and offers personalized optimization tips, it's worth listening to. You don't *have* to take their advice, but sometimes they can give you worthwhile tips - I had such an occurrence once, and I put in effect about 3/4ths of what they suggested, and my revenue did improve.
If you want to maximize your earnings, you should always be testing; blended vs non blended, text vs image, different colors, placements, in order to figure out what works best for you. I never NOT have some kind of test running.