I teach at-risk teens, and even jail doesn't seem to work. Many of them have undiagnosed or diagnosed (won't take meds) mental, learning or behaviour issues, so jail does nothing. It is just a place to crash for a few weeks or months, and it's usually much better than the nasty places they live in. We try to get to the root of why they are there and teach them positive coping strategies for their problems.
Most of my students are also addicts of some kind or another, as are their parents and other family members. So, without a good support system, or, the ability to actually get help, they don't do well.
Ms. Lohan, like so many other celebrities probably has emotional and other issues that will continue to follow her, until she herself is actually ready to get help. Jail, will probably just be an a funny embarassment that she'll tweet about, and she'll come back out, just as she did her last jail term (although it only last 1.5 hours in length), and resort to the same behaviour.
She has personal demons that she cannot overcome, and has surrounded herself intentionally, and unintentionally with people who support her toxic lifestyle. I fear that a tragic episode like a near death experience may be the only thing that persuades her that she needs help.
Being embarassed, losing movie roles, potentially murdering someone with her car, going to jail, and looking like a fool, has not worked thus far in convincing her that she needs help, so at this point, in my vast experience with this type of personality, it is going to take something major to do it...near death or perhaps or death itself...
Tiger