That's a huge problem in the coastal areas. They do need a long lead time to get everyone out, but on the other hand, people get really perturbed when they are told to evacuate (as we were for Hugo, Floyd, etc.) and then the storm takes a last-minute turn and misses.
IIRC, Hugo was expected to make landfall around Savannah until the 4 or 5 pm report - at that point it had made a slight northward shift, so ended up coming in just above Charleston instead, about midnight.
The authorities are really in a damned-if-you-do, damned-if-you-don't position here - if they wait until they are sure where it's going, not everyone will have time to get out. On the other hand, when they tell people to leave and the storm ends up missing, it's very expensive for those who evacuated (and there were those who actually died evacuating from Floyd who'd have been fine at home) and some people get angry.