A lot, and I mean ALOT of anime seems to form around the fact of: in order to get anywhere in the plot, there needs to be some convenience factor in the protagonist's life, to make room for weird shit to occur. Whether it is the fact that the parents aren't home often, or the protagonist just outright lives alone, they are all encompassing something I like to call, "Convenience Driven Development".
I was recently reminded of this plot device when watching Rozen Maiden. Since Jun no longer stays at home all day and has to work most of the time -- which I found mildly amusing, because Shinku had to wait around fro Jun before proceeding -- it acts almost like a wall, at least form the more supernatural part of the plot. Compared to past Jun, where he had all the free time in the world, it made the Alice Games progress quicker.
So now that we have an example where CDD isn't a factor, for the most part, where do we see these occurrences of convenience being used? Well, most of them are the ones stuck in high school, but they are not limited to those type of anime. Fortunately for me, the anime I'm going to pull from are going to be the high school ones, but this is mainly because they all are of this season.
Parents? Nah...
One of the more popular conveniences, being the non-existent parent; there are two this season that have absentee parenting, or they just don't show up often enough to interfere.
First one being Monogatari Series, which is almost irrelevant because the story doesn't revolve around the characters homes, or even high school, but as of Tsubasa's house burning down, this fact is far more relevant now. As a development point for her, she seem to be visiting her friends houses to stay and wait for a new house to be built. Not having parent there is basically why she could stay over at Senjougahara's home for so long, but eventually she had to change homes when her father came back.
The second anime that used this would be Kami nomi zo Shiru Sekai: Megami-hen, or better known as The World God Only Knows. We do see Keima mother in the first season every now and then, but third season is focused heavily on the whole "goddess stuck in previously conquered girls" thing; and since Apollo is incapacitated and staying at Keima's home, it was more convenient to not have his mom show up during these times -- but this was mainly Keima's doing.
Fairly Odd Parents
This is probably the alternative to not having parent in the house, and instead have super liberal parents that wont care if some stranger starts living in the house with no warning. The only one this season that fits the case is High School DxD New, but their is another which is Kiss x Sis -- however that is a bit different because of their parents got re-married and merged the family into one home.
But focusing on High School DxD, we have parent that will let almost anyone stay over, as long as they happen to be classmates to Issei. Leaving Issei in a place where he gets to sleep with two nude demon chicks pretty much every night. However, this is more or less to escalate the ecchi of the anime, rather than the plot, but it still is a convenience for something.
Inconvenient
To wrap up, I'm not trying to say that anime practice CDD are bad, but it so interesting that so many follow the same pattern no matter the quality of it's plot. I do want to see less formulaic high school anime, but really as long as it is interesting, I'm completely fine with iteration -- just make sure to have something in the series that is inconvenient, so it isn't just like playing on easy mode.