The lifestyle of a 15s international referee differs greatly than that of 7s. There is a lot more individual travel, unstructured time, and self-direction. I recently AR'd and refereed two test matches in the south of France. I arrived on a Sunday, AR'd on a Tuesday night, and reffed on a Friday night. The in-between time was mine to manage. It's important to keeps one's mind occupied and stay busy. Unfortunately, I did not have access to a gym, so I went out for runs and activation sessions by myself on a nearby field to maintain fitness levels. Luckily, there was also another referee there who refereed the first of the two test matches, and we were able to spend some time shopping and reviewing together.
The 7s lifestyle on the World Series is a lot more team oriented as we train together, eat together, and have numerous meetings together (technical sessions etc.) in the lead up to tournaments. We also adhere to a 'dress code' whereby one person is responsible for ensuring we turn up to all activities wearing the same gear to facilitate the team atmosphere. There is typically one day off during the week where people can get out and enjoy the city in which we are in. In-tournament, we are an extremely supportive group, watching each others games and commenting on where we can improve and how to better approach tough game situations.
Both refereeing lifestyles have amazing pros - one just has to take the opportunities as they come and own them and live them to the fullest!