At first glance, I was thinking of preparatory questions between the Bible teacher and/or a congregation servant (pre-elder arrangement) before the big day.
When I was at Bethel, late '60s, early '70s, a particular use of Your Word Is a Lamp to My Foot was announced to the family by Brother Knorr himself. The questions therein -- I believe this was a first -- would provide a means to determine the prospective JW's knowledge of the Bible prior to baptism. I recall his saying it would help stop ones coming in through the front door and going out the back.
So, then, having a thorough knowledge of The Truth precludes one's leaving?