I use a fair number of custom fields for Inventory, and they serve many different purposes.
Right now, they're just all crammed together in one section at the very top when the user edits an Item (as an example) in the native interface. Everything is in with the Item attributes. Similarly with Sales Orders, all of the custom fields are at the top and in one big group.
It would be nice to be able to create custom sections for these fields to help the intuitiveness for users. It would also be helpful for management if permissions, viewing, etc. could be managed at this section level.
One major use case here would be custom fields that are only used for automations. Anyone who has any level of customization will typically have custom fields that aren't part of a normal workflow in the UI. It would be nice if those could be separated, grouped, moved to a different position (say the bottom) of the UI.
Other custom fields are part of the normal workflow when a user is using the UI. It would be nice to be able to group and position those for an optimum UX.