When I was working at Etsy, I benefited from a very robust A/B testing system. Etsy had been doing A/B testing for more than 6 years. By the time I left, Etsy’s in-house experimentation system, called Catapult, had more than 5 data engineers working on it full-time. Every morning, I was greeted with a homepage that listed all the experiments that Etsy had run in the prior four years. When you clicked on one, you got a summary of what the experiment was testing (usually written by the product manager).