At the gym I trained at, we had a set of 2-3 coaches for compulsories and 2-3 for optionals. Once a week or so there would be some exchange between the coaching groups.
In compulsories, the team was divided up by L4, L5, and L6. I think L6 sometimes practiced on different days. We had one coach who mainly coached vault/bars, and one who mainly coached beam/floor. They all worked with all the compulsory levels, at different times or on different days. There were also one or two assistant coaches who would coach an event or supervise conditioning sometimes.
In optionals, the team was divided up into two groups by approximate size/age, to make settings easier. We had a coach who coached bars/floor/vault, and one who coached beam/bars/vault. The frustrating thing about this was that the bars/floor/vault coach was only good at coaching bars, both in terms of her instructions and her ability to give each gymnast attention. So my tumbling really lagged behind my other events.
In general I think it's good for a group to have multiple coaches over the course of a week on any given event, as long as the coaches communicate and plan what the assignments are so they can hit everything that needs work. Every coach has a different style and knowledge base, and sometimes having that variety is very important for gymnasts. Of course scheduling in a gym is a complicated beast so that is not always possible.