I was more surprised that none of actors died in the 12 years. What would they have done if Patricia Arquette had a freak accident? None of her sisters look enough like her. Reshooting the scenes are not an option, and editing new into the old would look bad

I was actually shocked that they covered 12 years without killing any of the characters.
You are so used to having stuff happening in movies, either somebody must die, or there must be some explosion, or alien invasion, or something. When nothing of that sort happens, you are shocked, and you wonder: what was the point of this movie?

Even the grandmother didn't die. Don't know why (as she wasn't that old) but I was surprised to see her at the end.

Yeah surprised the grandparents didn't die or something, my one passed away when I was around 13 or so.

I died of boredom.
This is me reincarnated.
Internet courage is such a yawn.

For me, the Samantha character was dead on. Lorelei's awkwardness made her prtrayal more real. As you say, a lot of teens act just the way Mason and Sam did in the film. They sometimes mumble their words and have little interest in conversing with adults.

Yes, I also read that she initially begged her father for the role, and that was why he cast her (although I also think casting your own child seems logical for a project like this for other reasons), but certainly at 7 years old she couldn't really have had a firm grasp on the scope of the project or comprehend the level of commitment (nor the likelihood of ending up in the public eye upon the film's release).
I thought she was wonderful in the earlier stages, but made less of an impact in the later ones, possibly reflecting her waning interest in the project. However, as someone who couldn't see myself ever pulling off any acting role, I have to give her kudos for her performance. While a lot of people seem to be critical of the Samantha character (finding her selfish/bitchy/whiny/unlikable, etc.), I actually think it was a fair representation of a teenage girl (and a big sister), and how insular their worlds can be. I have a 15-year-old niece and some of Sam's behavior reminded me quite a bit of her. Not a bad kid, just a teenage girl, and teen girls certainly do have their little foibles.
The further a society drifts from the truth, the more it will hate those that speak it.

I heard that Lorelei Linklater asked at one point for Samantha to be killed off, because she was tired of playing the role, but her father thought that was too "dark."
Its interesting. I've also read the Lorelei cried for days after watching the film. It was hard to see herself growing up and she thought she was an ugly child/teen. Obviously, she was adorable, but I can sort of see her point. This project was very hard on her privacy, she gave a lot of herself. After all, she's not an actor, and never wanted to be one. She's a painter and apparently a very private person.
I'm sure dad is very appreciative.

I thought perhaps Olivia's mother was meant to be a divorcee. It sort of goes with the idea that children of divorce make bad romantic decisions, which Olivia was outstanding at.
As far as nobody dying, completely irrelevant to what Linklater was doing with this film. Maybe if it were called 'Adulthood', then perhaps.

I heard that Lorelei Linklater asked at one point for Samantha to be killed off, because she was tired of playing the role, but her father thought that was too "dark." Anyway, the structure of the film is such that someone they knew could have died and the audience didn't know about it. It just wasn't anyone we knew onscreen. I don't think it's entirely outside the realm of possibility that of the immediate family - sister, mother, father, grandmother - none would die in a 12-year span. I assume that Mason's grandfather (Olivia's father) was already dead since the grandmother appeared to be single.
The further a society drifts from the truth, the more it will hate those that speak it.

I think I remember Linklater saying that if one of the cast members had died they would have worked that into the storyline, but otherwise maybe he just let things roll. If all the cast were still alive, I guess their characters got to be, too.
I suppose one or two of Mason's grandparents may have died (I remember seeing his dad's parents but not his mum's, though I may be wrong). I myself went from age 8-18 without any family deaths. And if you exclude grandparents I didn't lose anyone until I was 21. So I guess it happens.

I thought something would happen when they was throwing that circular blade at the plasterboard and a few other times

If I had been in one of the kids' shoes, I would have locked Bill Wellbrock out of the car, then broken the steering wheel and the stick shift.

If I had been in one of the kids' shoes, I would have locked Bill Wellbrock out of the car, then broken the steering wheel and the stick shift.

There are several times throughout the film when danger seems just around the corner. Looking at your smart phone while driving, throwing the circular saw blade, the second husband's rage.

I was sure it was going to happen during that scene where the alcoholic professor has an episode of road rage and drives like a maniac.
But it didn't. Thankfully. The likeliest victims in that scenario would been one or more of the children.

I know it's possible. I haven't went through a lot of deaths in my last 12 years. I just thought it would happen for sure for dramatic effect.

I went through that period of my life with no deaths in the immediate family. It's not exactly a huge number of people. Same for all my close friends. Plus in this case. no cast member died either. This hardly qualifies as remarkable.

Now that you mention it.that's a really good point to make. Nobody generally gets through a 12 year period without someone dying in their lives. Be it a grandparent, a friend, etc.
People say well, there isn't a Christmas shown in the film either, to make the point that Linklater wasn't trying to stuff every life experience into the film. I get that. But still, one death would have felt realistic.