The biggest advantage of using Drupal for a high school website is the ability for the staff to make edits without any previous web building experience. However, this is also the biggest disadvantage.
The root of the problem is a lack of communication between editors. The goals of the site become lost in a sequence of delegation, design standards eventually go out the window and goals of individual features are lost. Eventually the site loses its vision, falls victim to a design by committee and designers reach for tissue to wipe away their tears. Rest at ease, there is a very simple remedy to this common conundrum.
Ideally, the school should have a single person who understands the goals and design standards. He or she should meet with all site contributors and review its standards and goals thoroughly. If there are too many editors, meeting with each one individually will become impractical. A simple handout should suffice. Keep in mind, none of these remedies are fail-safe; the person in charge should also be responsible for periodically reviewing the site to ensure quality.
Only you can prevent design by committee.