It would be good to have an option (tab) within each event for custom fields.
This way you can just attach custom fields as necessary and see if you did not make a mistake or forgot to attach a field. Currently it offers a lot of possibilities but checking if all correct fields are attached is complex.
This would have two big additional benefits :
First, if would improve the normal workflow of creating a new event. Now you always have to keep in mind to "visit" custom fields" after to attach the correct field.
Second, if you copy an event, you would immediately have the correct custom fields in most cases.
