This has bothered me as well. Didn't she have a best friend who cared enough to find out where she was when she was not home by Sat PM.? Did they even try to call her? Who was she supposed to meet up with when she got lost. I assume LE has interviewed the friends and roommates extensively. This case has prompted me to check in with my own daughter who is away at college 1-2x per day. If I don't hear from her I know how to contact her room mates.
It's not unusual for college kids, other young adults to disappear for a day or even more. Hannah shared an apartment but had her own room. It would not have been unusual for her to have slept in on Saturday morning--clearly she was out to party Friday night, and no one would have been doing room checks or monitoring who came home or even did She could have hooked up with someone she met and willingly gone with that person, spent the night. Happens all of the time to the point that it's the norm. So everyone would be busy enough running around on Saturday, that I doubt Hannah or any college student would be missed. And then she could have gone out again Saturday night and done the same as Friday. This is not at all unusual.
In fact, that the roommates even got uneasy as early as Sunday, is a testimony to Hannah's regularity in being back at the apartment and getting ready for Monday classes. When she was not there Sunday afternoon, that's when her roomates started where she might be. Really, that's a day earlier than a lot of students would have been missed and maybe sooner than that. If she did not come back Monday night and IF roommates noticed she did not go to class, books and things untouched, no one saw her, that is usually the earliest that someone might get worried. Hannah was a straight A student, and put a lot of importance on her studies, so when she wasn't back that Sunday night her roommates got worried.
A few calls to some classmates that they knew she hung around with probably netted that "lost" text that was sent, and when they realized she was never seen after leaivng a party drunk and alone, that was probably what got them really alarmed. Parents were notified and LE and campus security were also brought into the picture. But there have been people missing for longer than that before the alarm was sounded and Police alerted. Some people are notoriously bad about disappearing, not telling anyone of whereabouts and do this a lot. Hannah was not that way, and she had roommates that were aware of her habits.
So, I think she was reported on the early side of things for a college student in an apartment off campus with her own bedrrom on a weekend.
Where I shake my head, is that she was out partying late at night, was clearly intoxicated, greatly so, from what those there told LE, and yet those classmates who did serve alcohold to her underage as well as likely a lot of other underaged students, just let her, a slight female, go off on her own that late at night. No friend with her, no one accompanying her. A guy did say he offered to go with her, but she said she was fine, and that was that. But I guess that is commonly accepted in the Corner. Drunk underage kids served alcohol with impunity and allowed to go off by themselves in that condition even in the dark at night. That is what happened here with Hannah. Not unusual in most off campus and campus scenarios either.