Reusing shapes - simple question

[STTrife]

I see the manual says you can/should reuse shapes. In my project, most of the object will be cubes. Would this mean it would be a good idea to just make 1 cube collision shape and reuse it for every object that needs a cube collision shape? Does this really matter much or is it just something you can do? Or do you need a different shape if the scale of the cube is different?

Thanks!

[CookieMonster]

Each size of the cube need a different shape.