My kids each applied to ONE. They did all their sorting beforehand. However, both were rolling admissions so they knew they were into their first choice by October. If they hadn’t been accepted, they had plenty of time to apply to other schools. They both also accepted that if something went wrong with our calculations for FA, they’d have to take a gap year, and that almost happened to one when the merit aid came in lower than expected (turned out to be a mistake on the ACT score).
It’s obviously not common… almost to the point of being unheard of. However, I don’t see why this would make you feel jealous. People do all kind of silly things in relation to college admissions. For example, collegeboard.org indicates one student took 30 AP exams during 2014-17. That an odd decision, but no reason to feel jealous, if you take a more reasonable number of AP classes.
Its people who apply to 36 colleges that are feeding the application frenzy and overflow. Its ridiculous.
Is this question related to your regret over not applying to Cornell? It’s not your classmate’s fault that you didn’t “buy into” the quest for an Ivy and are having second thoughts. If she gets accepted to an Ivy, it won’t be because she submitted 36 apps. It will be because of the one she submitted to the Ivy. You can’t get in if you don’t apply.
You’re in at Tulane. Is it affordable? Do you have other affordable options? If you’re not satisfied with your results, you can take a gap year and create a new list. I’m not sure that a 32 ACT is competitive for an Ivy, but if you’re going to regret it if you don’t apply then you should submit an app. Either way, I’d quit wasting time analyzing your classmate’s application process. The one that really matters is your own.
Edited to add:
I’m not really clear about your grade or ACT score. Are you a senior now or were you in 2016/17? This thread makes it sound like you’re currently a senior with a 32 ACT. The 11/2016 thread says you have an older sister at an Ivy and your parents are Ivy grads. If you’re a senior and really want to apply to an Ivy, take a gap year and apply.
My daughter applied to 16 schools. None are safeties (she could not be convinced to apply to a public university she could commute to, the ultimate financial safety). I could not talk her down; she had good reasons for applying to each, and the ones she only likes instead of loves are the ones she is most likely to get into so can’t be taken off the list. She wrote strong, individualized essays for each and has tried to demonstrate interest to all of them. She finally admitted that, although it wasn’t more than she could handle (because she handled it!), it was as much as she could handle. Five of the applications were free, but I hadn’t really thought about the test score fees and the CSS Profile fees. Plus her twin brother applied to 11. (My credit card really took a hit last month. 
)I do wonder how anyone could possibly do a good job with 20 more applications and also go to school.
After reading your other posts, it doesn’t sound like your classmate is the only one competing with an older sibling.
If you’re still in high school, please note that you shouldn’t be using your sister’s ID to post in CC. You’re supposed to create your own. If you’re a college freshman who regrets your choice you can look into transferring, but you should understand that it’s extremely difficult to transfer into an Ivy.
MODERATOR’S NOTE:
Closing thread. As there are apparently numerous users using this account in violation of ToS, It has gotten too confusing. Additionally, I think the conversation has gone as far as it can go.