I think that it's important that people have named jobs to do, it gives them responsibility and helps keep their interest. It obviously helps to try and match their jobs to things they might be interested in, although getting a new job can stir interest.
For me I find it key to have an Adventure Training Officer & DofE Officer because I'm really keen on making sure the Squadron does plenty of both. I also find a Shooting Officer important.
Beyond that I have a First Aid Officer, BTEC Officer, Radio Comms Officer and a Media Officer.
It's important to give people terms of reference and make sure they know what they are responsible for and what you expect of them, this also allows them to say if you are giving them too much to do.. For example my First Aid Officer is expected to get cadets Heart Start trained within 3 months. All cadets YFA trained within 18 months. To advertise and twist arms for staff Courses and to run 1 First Aid Exercise a year. (This is done as part of the buildup for the Wing First said Competition).