I’ve always assumed that the rule is: any statement on any issue stands unless it is contradicted by a more recent statement. I can’t point to anywhere that outlines this policy, but it just seems to be the way JWs approach teachings in the literature.
It’s true that the older a statement gets then it begins to raise a question whether it is still teaching, even when it has not been subsequently contradicted. An often cited example is the teaching about 7000-year creative days in Genesis, which was often stated in literature especially leading up to 1975. If I remember correctly the last statement to this effect was the 1980s, or earlier. So is it still current JW, or not? I don’t think it is clear. Unless someone has more information on this topic?