Yes, raiding like this is a good way of weakening your enemy with little effort. You can save resources and population by having one group that keeps moving to the different areas that the enemy is getting resources instead of having troops at each spot. If your enemy responds by putting troops everywhere, then you successfully made him waste resources.
Noob: HAHAHAA! FEEL THE WRATH OF MY MUD-MAN ARMY!
Good Player: Time to launch the Ice Block.
(Mud-Man Army is completely destroyed by giant Ice Block)
Noob:.......
(Noob quits game)
Good Player: