Kevin, that was my thought too because but then I realized my mistake going into the movie.... I thought it was a time travel movie, then someone corrected me and say, no. Look at the title, it's called "Premonition."
So here's my theory, after reading a bit about it last night.
-- SPOILER ---
The first Thursday, when everything is normal (no scars, she's putting stickers on) is a premonition. It's not REAL. She is not really "living it." In that premonition, she's getting the bad news. Her husband did call her before he died, but remember -- she said she didn't remember when that voice mail was left. Because.... da da... it hasn't happened yet. Nothing has happened yet. She has a premonition of being notified that he's dead. But is he really dead? She asks that questions a few times afterwards, and that's why she wants to see the casket on Saturday....
WHICH, is also a premonition. Again, it hasn't happened yet. But by then, the future she sees has changed because of her present real life, and what she does in "real time" -- her behavior, confusion, etc. has affected change. She was supposed to put stickers on the window, but because of her premonition, she thought she did, but she hadn't. And she is so out of it on Tuesday that her daughter has the accident. But Saturday is a premonition.
So, I think anything we see AFTER Wednesday are premonitions and they change based on what she does in her real life, which is Sunday through Wednesday. Using her knowledge of what may happen in the future, she tries to change it. By the end, after she talks to the priest, she realizes what is the most important thing.
They make it, supposedly, easier to understand by making it a whole week, starting with Sunday and ends on Saturday. Also, they make Sandra draw out the whole thing on paper...
I was disappointed by the ending, too, because I was looking at it as a "time travel-change the history" story, and the whole scene just plays kind of stupid. She knows a semi is going to come but she's like chatting with her husband and saying "I love you, too..." So yeah, I got frustrated with the stupidity. On the other hand... I understand. She never really saw what happened on Wednesday. It wasn't in her premonition (except for a very brief moment, when she first got to mark 220 the first time). In her Thursday premonition, she never really heard the details of her husband's death... so in her mind, she really thinks she's saved him by having him stop, until it's too late and the car stalls. I know it's still lame.
But the idea, I think, is that she can't change what is inevitable. Jim is going to die either way -- whether it is because of her, or because he has a change of heart about the other woman and he turns around, but it's part of the cosmic karma, I suppose, that he has to die. But by reconciling with him, expressing their love for each other, and also by witnessing the death herself, she has closure... the whole ending is about "moving on." It's philosophical.
So while I think the ending is lame, I do understand why it's there, and what the philosophical aspect of the movie is about. And after understanding the "premonition" thing, I also understand my first impression about the time line was wrong.
I still don't understand, however, why her real life happens in random order. Why did she live out Monday first, then Tuesday, then Sunday, and finally Wednesday... That I can't explain. Or are all of those premonitions too? The only thing I can think of is that it's the only way the writer can make her behavior change what happens next. They want to make it a complicated mystery. But I think they could have easily done it by having her go through Sunday to Weds in sequence.
I got it. I understood it. The end just dove tailed to a hollywood sugar coat. I was wrapped up in the twist-around days stuff...but noticed some incongruences with it too. The daughter, on Thursday (the day the movie began), did not have her face all cut up...and Sandra was putting the stickers on the window. The daughter should have had her face cut up on that day? Sandra, while driving to the scene, decides (with that all too whimsical smile) to let her husband live...but then says, "if you love me, turn around" ON A BLIND HILL! He would have lived had she said, "Stay there. I'm stopping behind you". It would have been more believable if she had decided he had to die...then if she gave him that idiotic advice, we would understand why she gave it. revenge of the almost cheated upon wife.
I really liked the ride it took me on, but I didn't like the stop. I was jostled by the utter boredom of the ending. stupid, stupid, stupid. So there. I have spoken.
) we got in an argument, wherein it ended with my going off on a rant about my theory that Sandra Bullock is, actually, a man. Come on...Bullock? This means, quite literally, castrated bull. Plus, she has a very pronounced adam's apple. Not too mention her facial structure in general.