The spiritual maturity described in Heb 5v11-6v2 is not only doctrinal but also spiritual perception, in 2Chron 18v1-27, Jehoshaphat knew that, Ahab's 400 prophets did not bring the word of the Lord, his spiritual maturity was such that he perceived they had no anointing whatsoever, hence he asks Ahab to inquire of a true prophet, hence Ahab produces Micaiah, whom Jehoshaphat perceived to be a true prophet speaking God's word with an anointing on him.
This kind of spiritual perception is received by having prolonged communion with the Lord and sitting in His Presence, it is not a perception with the mind but with one's spirit with the Holy Spirit upon one.
Yahweh Shalom