Overlapping Batches
hackerschool.com
hackerschool.com
As long as there is sufficient staff to handle the increased number of students, I think there are only advantages to having overlapping jr and sr classes. Every student will get a chance both to mentor and to be mentored. Both are helpful for learning.
The total number of students isn't increasing. Two batches will overlap, but the size of the batches has been halved.
Really, the best part of overlapping like that is that you aren't just accessing what the last cohort experienced, but the distilled wisdom they got from the cohort beforehand.
Having incoming members talk to existing ones is a very important part of maintaining and expanding institutional knowledge. It's especially important to foster communication in organizations with high churn rates.
That said, your point is true in two ways (though I don't think in the way you intended it). First, we try to make every batch better than the ones before it. That implies that it's always better to come to a later batch (I think it's certainly true that it's better to come to Hacker School today than a year or two ago). Second, every batch has been an experiment for us: we make lots of changes (big and small) and we never know a priori how well they'll work.
I actually see being in the first rotation as an advantage! I get to start Hacker School with a core group of 35 people. I have an easier time getting to know everyone in the batch and all of the facilitators when there are only 35 of us. Then, after a few months, there are suddenly 70 people and I can see how Hacker School runs with a larger group.
I see being in the first rotation as an opportunity to experience all possible configurations of Hacker School. Furthermore, I'm excited to be able to help shape the culture by virtue of being part of the first group doing it this way.