2 Timothy 2:15 AMPC
Study and be eager and do your utmost to present yourself to God approved (tested by trial), a workman who has no cause to be ashamed, correctly analyzing and accurately dividing [rightly handling and skillfully teaching] the Word of Truth.
Many will tell me that the workers (born again Christians) must learn the Bible and be ready in season and out to quote scripture in any situation. That we must listen to sermons, read books written by Christians, as well as faithfully reading our Bibles. Even reading multiple translations and digging into the original writings to glean the truth. Study to show yourself approved they say.
I believe they are missing the boat. Look at who Paul was writing to in this book. Timothy nor any of the men he was about to face had a Bible to read. It was not completed yet. Even if it had been written most could not have read it and there was no way to duplicate the pages without the printing press that would be invented over 1,600 years in the future. Sure, they had the Jewish torah if they happened to be Jews and had memorised it.
John 14:26 AMPC
But the Comforter (Counselor, Helper, Intercessor, Advocate, Strengthener, Standby), the Holy Spirit, Whom the Father will send in My name [in My place, to represent Me and act on My behalf], He will teach you all things. And He will cause you to recall (will remind you of, bring to your remembrance) everything I have told you.
The "study" occurred as they stepped out led by Holy Spirit to do what the great commision had called them to do. They preached the Good News, saved the lost, and healed the sick! Did it always go as planned? I do not think so. They learned through the experiences they had as they went as Holy Spirit taught them all things.
I believe true knowledge does not come from what we glean from others as we hear their words. It comes as experiential knowledge gained as we go forth listening to Holy Spirit as He guides us into all truth, as we practice His presence and allow Him to come upon to do the work of Jesus.