Inadequate security config poses serious data fraud risk and prevents the users from using UI. Not to mention the very costly and time-consuming D365 security project.
Download this eBook and find all you need to know about creating D365 custom security roles.
You should be thinking of security design as a critical part of your Dynamics 365 F&O implementation and maintenance.
While you make fair use of the security provided within the application, consider using a separate tool like Security Setup for enhancing data security and shortening the time of security projects to minimum.