It is largely dependent on the professors personal preferences, which is not always the most convenient for students. This is the most importatn part of the syllabus to me. I think all classes should be required to have course hoempages and all instructors should have homepages as well. Don't ever get rid of or not put that section in the syllabus vital to students ability to contact and clarify during the semester web pages are very useful. Later doesn't usually happen.
Office hours can be hard to put on a syllabus because they can change.
Before the semester you usually do not know how your schedule will work out. Every teacher grades differently, but its important to have a basic idea of how you should handle the material presented to you. That is of course that the professor then continues to follow the objectives throughout the semster. This would be beneficial, especially for writing classes. Then there is no questeion on what is expected This is usually the most vague area of the syllabus.