My theory is some applications received interview invites earlier than others because the initial application review is done by either a paid application reader employed by the Admissions Office, or current students part of the Johnson Admissions Group (JAG).
The readers or the JAG volunteers make a recommendation to the admissions officers on whether to extend an interview invite. It's entirely plausible that if your application winds up with one of the JAG volunteers, they take a bit longer to review the entire application than the professional readers to, and perhaps the admissions officers treat their recommendations with a bit more caution? And that results in you getting an interview invite later on in the process.
Well, that was your "trivial theory based on pure conjecture" for the day.
But who knows what's going on behind closed doors in the admissions suite. With everyone's admissions decisions coming out on Dec. 17, it makes no difference whether you get an interview invite in early November and mid-December. Your chances of getting through will probably stay consistent and have no bearing on the timing of your interview invite.
So hang in there R1 folks, there's plenty of interview invites still to be had.
Cheerio.
P.S. Btw, someone on BW reported receiving an interview invite today, so perhaps there isn't that much to the Tuesday/Thursday thing after all?