I have custom Record views with multiple columns and I make extensive use of span values.
Whenever a field that is in the view is deleted from studio, Sugar rebuilds the entire view. The view is mangled and has to be restored from backup. A workaround is to manually remove the field from record.php before deleting the field.
Ideally, the custom view should not be changed other than replacing that field with a blank.
thank you,
Francesca