I think I have mentioned this before but had a similar issue where this would have been super handy recently. 🙂
What would be awesome and save a lot of time would be a mnodification to the ‘Page Link’ field where the user could either select a page or a custom post type like they can now but also have the option to type an external link.
This would elimanate the current method where I would use a select field to choose one of two fields defining a page link or an external link.
Hope that makes sense! 🙂
This has been requested many time. I don’t know if it is on the developers “to do” list. If you want, the best way to get this request to the developer is to submit a new support ticket https://support.advancedcustomfields.com/new-ticket/