How useful are inspired and truthful historical doctrines? (Which were not canonized.)?

Are historical doctrines (which were not canonized) useful in studying the Word of God? Surely though not all works are God-breathed some are inspired or blessed? Discuss. I am referring to doents such as The Ascension of Isaiah, The Gospel of Bartholomew, and even the Dead Sea Scrolls. Perhaps you would call it Apocrypha? Waste not your time in petty remarks lest you be judged by a wrathful God.