The majority, when I was in, didn't have a clue, and it must be much worse now, as they have dumbed everything down, JW's just look up a verse on their Tablet, (if they can even be bothered to do that), read it, and then think they know what the Bible says.
I was considered a real student of the Bible by my Cong. but I realise now that I knew nothing really about the Bible, and little of what the writers were really saying, being a born-in I saw everything through WT spectacles.
At least, back in the day, me and a good number of my contemporaries, though a minority, could make a good fist of explaining our faith.
You would be hard pushed to find a JW who could today, Elder or not.
Blondie, I was kind of sort of that elder, maybe a bit better. I did know that Moses allegedly wrote the first 5 books. I could name them. I knew what they were about. I knew the Pentateuch (first 5 books) was followed by Joshua, Judges, and Ruth. If I tried really hard, I would probably come up with the 2 Samuels, Kings, and Chronicles after that. Then I could easily remember Job, Psalms, Proverbs, and Ecclesiastes, but probably would forget Song of Solomon. I generally knew what each of those books was about.
I would be kind of lost after that. Of the books named for the prophet writing them (and Lamentations), I would remember Isaiah, Ezekiel, Daniel, Jonah, and Malachi, but often forget many of the others in-between and have no idea of what order they were in. I did remember that Malachi was the last of the Hebrew or Old Testament. Of those books, I had a good recall of the ones I could name above and what they were about (except for Malachi) but of the ones I would forget, I would have no real idea what was in them. (I didn't know the difference between Obadiah, Habakkuk, or Haggai or the several others.)
I was much better with the New Testament. I was very familiar with the 4 Gospels and that John was very different from the first 3. I knew that Acts followed and was a history of the missionary activities of the early Christians. I knew that the "Letters" came next, mostly written by Paul and starting with Romans. I am sure I would get the order wrong after that. I used the memory aid that the "T" books were in a row and were alphabetical- Thessalonians, Timothy, Titus. I would remember Hebrews and the Peter and John books. Jehovah's witnesses were heavy on the "Letters" to browbeat the congregations, so I generally knew what was in them. I would forget Philemon and Jude, but of course knew Revelation at the end. And from all that study in the "Grand Climax" book (sounds dirty), I was very familiar with Revelation and how it foretold so many things in the 20th century about the establishment of Jehovah's Witnesses.
I was good at using the table of contents to find a book of the Bible quicker at a meeting. I did hear "66 books" enough to know that, but couldn't tell you how many were OT and NT. To be honest, I knew the Bible snippets that JW's use (phrases) and that you could look up most of them in the back of the NWT and find that scripture. (I don't know if the new NWT retains such a feature as I have never looked into it.) I felt that I was not so good at memorizing but was very good at USING the Bible. Of course, I was actually only good at using the JW Bible in the JW way of using it.
I have heard comedians say that Christians who feel that the Bible is God's book for mankind, God's primary way of communicating with people, should read that thing every day and know it very well. To be fair to Watchtower, they generally say the same thing to the members, but they mean that they should know where all those snippets they use heavily can be found and how to use them in a way to stop contrary thoughts or comments about the organization.
Well, I think you know that I was not a memorizer, but understood not only the WTS explanation having had to look it up when I had my questions. Their "answers" just led to more questions on my part.
I recognize that there were a few that did not repeat WT words by wrote or just repeat the scripture, but not many.
I always used 3 different bibles when looking up scriptures.
I have found that many jws do not know that the phrase "governing body" never appears in any bible, not even the NWT, but I have had a terse discussion with many jws about that and the look on their face when I showed the Acts 15 was priceless.
Many jws felt I was weird because I did know things about the bible....one even said that only the scriptures that mattered were what the WTS used in their publications. I used to research every verse in the WTS publications when my husband was school overseer (because so many elders cancelled out or did not prepare the Bible reading). It is amazing how many are never used...leaving it up to the individual jw interpretation (not good).
What I did remember and still do is how to use the WTS own words to hang them.
It is a paint by numbers approach to bible study. You can paint like a master, just put the right colors in the right places.
Same thing with a "bible study". Read paragraph, ask question, householder gives answer, repeat.