Do BCG Summer Internship 1R interviews come out in waves or all at once?

I know a lot of people heard back from BCG on July 10 regarding first-round interviews for the summer 2027 internship position. We were told that we would hear back either way by July 15. I was wondering if, in the past, BCG sent out interview invites in batches, or if my application process is pretty much over if I didn't receive an invite on July 10. Insight into how it's worked in previous years would be very helpful. For reference, I applied to the NYC and Chicago offices.