0 strategy in towering at all, really. Doesn't even show how good a guild is, just how much life they waste away at a tower. That's the difference between towering and spar. You can throw your guild into a gs arena and lose every single time, but you can throw your guild at a tower enough and eventually you'll hit a goal.

*note* I don't mean "you" as in your personal guild, whatever it is, just a second person view.