Well I just used the night before to cement anything I wasn't sure about but trust me; I was the only person who said the exam was do-able, everyone else complained so much >.>
Cramming is not a good idea in any upper-level discipline. Even for the brightest of the bright, the most important piece of the learning experience is time. If you give yourself one night, there's no time for the information to soak in and really be retained. As far as chemistry goes, you need practice (which takes time) to either learn the process or memorise everything you have to do.
On the other hand, the physical sciences just don't come to some people :/.
Actually I spent the night before studying. The work is a bit too advanced. The teachers cram too much work into too little time and don't give us time to take it in