Do I need a nonce in my custom metabox?

I’m setting up a custom post type with meta boxes only for this CPT.

The model I originally started working off did not use nonces in the meta boxes, but as I read more, it seems it’s a common practice to include them.

But I’m getting mixed signals. Someone suggested adding a nonce to each custom meta box (even though it doesn’t add security to have more than one?).

Others: the nonce from the main form will do the job, so no need to add any at all.

Is there an actual security benefit to adding a nonce in each custom meta box? Or even in just one of them?

Thanks!