here are my thoughts on your question.
There are definitely things that we expect team members to carry over from one season to the next--knowledge and enthusiasm. That's part of our Core Values.
What are the Core Values? The members form a team. The team does the work. Everybody learns. We honor the spirit of friendly competition. Discovering new things is key. We share what we learn.
It's fairly common for teams that use MyBlocks (or the equivalent) in their programming to adapt those from year to year. As a design judge, I'm always interested to hear how teams have built on previous knowledge. It's always been clear whether the team members did the work and actually understand what's going on in the programming. That's much better for the team, in terms of discovery as well as in being eligible to win awards.
Not everyone on a team has the same role or does exactly the same things. So some members may have had experiences over the summer before the team was fully formed for this season. That can be okay.