One of the keys to writing a persuasive brief is to make it as short as possible. Obvious, right? Then why does it seem that legal briefs, at least at the trial court level where I primarily practice, keep getting longer and longer? (Recent examples: 35, 50, and 60 pages.)
Lawyers will say that they don't want to waive any appellate arguments by failing to include them in a brief, but depending on the issue, leaving an argument out often won't trigger waiver. Even if it does, most briefs can still be reduced by half without any risk of making them less meaningful.
This same principle--keep it as short as possible--can be applied to trials too, as a colleague reminded me at lunch. We were discussing too-lengthy briefs, and he said he prides himself on keeping his trials short too, doing in a week what other lawyers often take a month to do. In a recent mass-tort trial, for example, he reduced hundreds of hours of videotaped depositions to forty hours, then to twenty, then to eight, then to four.
It was the four hours he went with, not the hundreds. I'm sure the jurors thanked him for it.