Mailstand's A/B tests are run on every single step. Here's an example of how 3 different contacts could go through a campaign where you are running A/B tests.

The benefit of A/B tests templates on each individual step is that over the course of the campaign you can turn on and off templates that are not doing well within a particular step and we will automatically adjust to send only the variations that are "ON".

You can turn on and off steps by selecting the toggle under the steps section of the campaign.