Well I think either one is fine (interested if the experts have an opinion on which they track and why) but for me I track the back row players. They are the ones I will call a back row attack/block on so I keep them in my head. So I have 3, 8, 11...if any of them do illegal back row stuff I call it, if any of them are close to doing illegal back row stuff (jump and attack the ball close to the attack line), I signal they are safe in what they did. Seems easier to me, if anyone else does anything I don't care they are front row and can do that
Setters.....I have never tracked setters, never cared! I was told that tracking setters helps you if/when you go without a card. They are the most active in a game (always have 2nd hit well they are suppose to anyway
) so if you know where they are and the person to their right and left you have half of the lineup allready. Again that is what I have heard but who knows, I always have my wheel! Also I think they are important in that some like to dink it over the net and that can be illegal depending on height of the ball when they are back row if they are at the net so watching for that is important, again I keep all three back row players in mind so to me the setter is just another player that can't do certain things when they are back row.