A clip is not a grade -- these are two different terms.
A clip is a physical piece of material, a file in a specific codec (DPX, R3D, ProRes, DNxHR, etc.). A grade is a specific color correction stored as a node or a series of nodes in a Resolve session.
Shared Nodes, Group Grades, Timeline Grades, and individual clip grades all have their specific uses, but there is no one "best way" to work. I know what works for me, but I strive for simplicity and reliability over everything else. I'm a little suspicious of Shared Nodes and I avoid them at the moment, but some people use them successfully and are fine with them. Some are fans of Local & Remote Grades, and that's another feature I rarely use, but some do and there are positive points for it (all explained in the manual).
I'm a big fan of using Gallery Grades and Memory Stills to apply a specific look across many shots of a scene, then I dive in and trim each shot as needed so that everything matches uniformly. I don't know if this answers your question, but this works for me.