Organize your teams and checklists into departments
Use departments to section off your team members and checklists into separate "sub-accounts", with unique checklists, users, and reports.
In this case, Sarah, John, & Kelly will have access to everything, since they are within the main account. James & Mary can only use IT checklists and won't see anything in the other departments. The same goes for Susan & Eric in Accounting (they can only use those checklists) and Bob, Jeff, & Allison in Sales.
If you have multiple locations for your business, you can set each one up as its own department. This will help your teams organize their checklists more easily and manage team members more easily.
If you want to have checklist templates and runs that are hidden from other people in your organization, departments are how you would accomplish that. You can put your team into departments and create a separate department that they are not within. With that sturcture, they will not be able to see any checklists or activity in that private department.
How to do this
On the page for managing your team, you'll see a button to manage departments.