Each and Every situation is different, it depends on the people, their values etc etc.
However having said that, I think living together before marriage is a good idea, you do get to know the person better, their habits, good and bad.
I rushed into my first marriage, but with my second I still chose to live with my husband first, we married within four months of being together, I was older and hopefully wiser this time, we are still together 12 yrs later, so heres hoping, fingers crossed.