I agree. This is a guest post on our blog but my opinion is that one should do a lot (and lot) of small A/B tests coupled with a couple of big, large scale test

I agree. This is a guest post on our blog but my opinion is that one should do a lot (and lot) of small A/B tests coupled with a couple of big, large scale tests. Interestingly, most of our A/B testing case studies have been about small changes leading to large conversion rate changes: http://visualwebsiteoptimizer.com/case-studies.php http://visualwebsiteoptimizer.com/case-studies.php Although "grand slam" tests are essential so that you don't get trapped to local minima.