Most entities are most commonly associated with a small amount of relationships, even if they can have a lot of them. I'd like to see the possibility to mark a relationship type as "default for entity0"/"default for entity1", which would show it by default in the edit page for the entity. For example, the artist-work "composer" relationship would be default for works, while the artist-event "main performer" and the event-place "held at" relationship would be default for places. These could be shown as separate "boxes" inside the relationships section, with an "add other relationships" button under it.

This would allow new users to get familiarized with the concept of relationships from the beginning and also find the ones they are more likely to want to add easily, and would probably save time even for many expert users.

Additionally, a short explanatory message could be added for each default relationship, with some info about how to use it.