How Long Do You Need to Run a Test?

The more granular the change you want to be able to identify, the more time you need. This is too take into account any sort of diversity, or seasonality, weekly seasonality that you might have in your custom behavior. But as a rule of thumb, we always say that r even if you have enough traffic and your change is not too big that you need to it should always be run for one or two full weeks cycle....