That's another story. The point of the Trench gamemode is to be able to pick up blocks and create your own stuff (or destroy the enemy stuff).
That may be said is spam, but there's no other way to do it correctly. 4x cubes? Perhaps but it will be stuffty.
Normally the Trench maps have big bricks, but they can be modified. You are just using it so everything is destructable, but there is no point.
Trench = Gamemode with map(s?).
TDM = Gamemode
What you're doing = Map with unnecessary spam.