DeletedUser5399
Having 5 Watchfires gives a defense boost of 20%. This bonus is to small to be useful against PvP players who can have up to 150% military boost. If you're positively sure that you won't get any defensive GB's in the future then I would suggest to spent the eggs on other things.
Watchfires are only useful in defense of your town. Not in PvP or attacks/battles of any other type. I only have 4 Watchfires but already I can see that the little extra defense helps in defending my town when some neighborhood bully attacks. ^_^