Teachers are the brain of the school and with knowledge transfers happen.
It is important to be able to accommodate their needs to the fullest.
Teachers like to specialise and focus on certain courses. Often there are also pre-requirements involved with teachers teaching the specific courses. Some teachers would like to have certain courses at specific times. E.g. Cooking courses before lunch break.
Very often teachers cannot teach at specific times on this schedule. Teachers might be involved with office Administration in the morning or they might be teaching at another school or university that takes preference, and only help out on a part time basis at the school and can only come in at certain times of the day.
Some teachers also like to have a preference of the rooms that they are teaching in, which needs to be accommodated. For example, a computer science teacher needs to teach in the computer lab.
Being able to accommodate the teachers needs the optimum results in the smooth running of the school.