Depends on the Command and/or Base.
in a perfect world, for each division you will have one Chief (E-7), one division officer(usually an 0-1 to 0-3), one department head (0-3 to 0-4) whom report to the executive officer and Commanding officer of the command.
For particularly large divisions, say maintenance divisions, you would have a chief in charge of each branch.....electronics....electrical....... welding, etc whom is knowledgeable of that same rating as the people they are in charge of. On board a ship, usually a division has from 8 to 30 people, depending on if its a technical field, or just the paint scrappers.
A division can sometimes have more than one chief if its particularly large...like engineering or maintenance but sometimes will have a higher ranking chief (E-8) to handle the multitudes of paperwork (evaluations, recommendations, individual counselling, maintenance reports, part orders, repair status reports, ship readiness reports, etc, etc, etc)
That's it in a nutshell.
Typical engineering i've seen on ships were 150 people, 5 chiefs, 3 senior chiefs and a division officer.
Electronic repair shop..10 techs, 1 chief, 1 division officer.
Then there's the out of the ordinary commands like Assault Craft Units where the detachments themselves have like 6 to 10 boats to them, each boat has a crew of 8 people and 2 or 3 chiefs on them (1 pilot, 1 navigation and can't recall the name of the middle guy...but the middle guy wasn't always a chief), then there's the support teams for the boats. Then there's the support crew for the boats whom pretty much fit the numbers for an engineering division.
This is what i've seen, because there may be a "on paper" idea as to how many there are supposed to be, but it doesn't work out that way in real life. I've been in divisions where we didn't have a chief for a year, and i've been in detachments that was excessively top heavy. Its all up to how well the detailer does his job, the timing for cutting orders, new graduations, waiting to see if someone makes rank or not, etc.