Using A/B testing has become a common practice to find out winning variance. But every-time you use it you are inefficient and you loose for the bad ones. Also winning is not guaranteed to last for long. Trends change, customers change. Ideally you have to be in a constant flow of testing, and trying the new thing, with minimum loss. Let’s not forget to also take personalisation along for a ride, and mix in some recommender systems, and see what we got. It is going to be a bumpy ride. How we solve the multi armed bandit problem is going to be the answer, or is it?