Why it matters: Quite often users can do some unintended actions that didn’t lead them to the desired result. In that case, you should give them an opportunity to return and start over again. So, they won’t get frustrated, feel guilty, will recover easily and keep moving on the flow.
How to test it: Firstly, make sure that your navigation system allows going back and that all actions can be undone if necessary. Then, during usability testings, create scenarios where users are most likely to perform the wrong action and check if they can recover easily after.