In cases where you know from which angles an asset will be viewed, you can use that information to optimize the assets accordingly. For example, side scene geometry in the level that's only going to be seen from the playing field. Rather the building assets custom for that case, you could just use what you got and optimize it through cameras scattered in the player area. You can instruct Simplygon to cull anything fully occluded, but the visibility information can also be guide the reducer and the material caster to keep more where the geometry is most visible.