I voted the 'too many' option because most of these towers can just idle for most of the day, but really they should find instead a way to stop guilds from adding and removing members constantly.
The only thing that I can come up with is adding a restriction that stop members of a guild to help their towering guild until they've been in the guild for a certain amount of time (1 week? 1 month?). But if you do something like that then I think you need to start adding more rewards after the 1000 hours achievement so they will continue towering on that tag and not just join another guild.