The effectiveness or not of the old Theocratic M. S, depended upon the skills of the Elder in charge , in the old days we had a guy who was very skilled, and taught many to be good Speakers. Then we got a guy who himself had no mastery of the English language, was hardly literate, and was a total joke, why the Elders foisted him upon us I know not !
Nobody improved of course under his "tutelage". I should imagine that now anyone who turns out to be a reasonable Speaker does so from natural talent, not learning skills from any JW Meeting !