yes its important , like almost everything !
Almost always you can simplify your object in a simpler structure.
You may even create 2 box collision, one for the vertical wood, one for horizontal metal.
simple collision made by unreal can be often used, but as you can see they
dont follow the shape of the object.
if you dont need too much precision , is okay to use them.
if you need full precision , make the collision yourself.
to maximixe precision but get a performance impact, you may use all the mesh to collide
This is called “use complex collision as simple”.
2 cube have only 16 vertices.
that hammer have a lot more like 80 ?.
i am not an expert on how much deep calculation goes, but
simplification are there for a reason , so 16 is better than 80 