Saved mappings doesn't work for all use cases.
When you have saved mapping field with Organization Name (match to contact) or Email (match to contact) fields set and you try to import contact using the mapping id, the Organization Name or Email is not pre-populated unless we have column first row set to Organization Name or Email. Checking civicrm_mapping_field table found out that it stores the label in civicrm_mapping_field.name field (i.e saved as Organization Name (match to contact) or Email (match to contact)) and is matched against the metadata from DAO class which has '(match to contact)' missing in title.
Organization Name (match to contact) or Email (match to contact) fields are one of the mandatory field for contact import process. This was working in 5.13 but recent upgrade to 5.19 failed to populate the field.