In line with BluesBrother, I remember a time when "extra research" was a prized bragging point of the ultra righteous during a watchtower study. Of course, 99% of that research was to be done in the aid book or similiar, but still it was a trump card.
Now the witnesses are scared to even do research in their own literature, for fear they will stumble on old light. Lol... funny when you think about it. The paranoia of getting out of line is at an all time high.Sad on the other hand though.
The equivalent of the "extra research" comment today is a comment on the illustration in the lesson before the conductor gets to it.
In answer to the OP - The witnesses are not allowed to be bible students. Hell they can't even study 90% of their own literature since it's considered old light.