Its a good question, honestly, and one I am curious about. We know that the May 29th one came about because the May 23rd one had technical issues and they were unable to get good data from it.
From the sounds of it, this one looks to have been much more successful. My assumption is that there won’t be another unscheduled one before the next test but I am curious if because of this unexpected test happening if the schedule would have changed.
They told everyone on the forums in the above linked thread that everyone who was in the previous May 23rd test was going to be in the May 29th test. They don’t send emails out for those kinds of things.