Reluctance length

[Becky]

The specific length of a persons beard (or hair) which makes them [reluctant] to [cut it off] as they have never experienced such a length. Or, because they feel that their beard has become important to them, like its their child.
Note: Often occurs in teenagers and young adults who are notoriously shit at growing beards and tend to cling desperately to any facial hair they can [muster].