Length of submissions
Closing submissions should normally last about 30 minutes for each day the hearing has lasted.
The most common mistakes in closing submissions are excessive length and irrelevance. It is very easy to speak at great length, while doing nothing to help your case. A short, relevant submissions will almost always be the most effective one.
Like most similar maxims this rule should be broken regularly. Some short cases deal with complex legal points that will require extensive discussion; some long cases are best ended with a few sharp, pithy words.