LOD is not always that important as you stress it. Current hardware even does not care much about LOD. It can "eat" polygons without any problems. The number of draw calls and the size of textures are much more important. When I am testing my sci-fi and fantasy scenes in different engines I often realize that downsizing textures and reducing shader quality affects the FPS numbers much more than reducing polygons.

Although it is important to reduce polygons for collision detection, physics or other CPU-related content. In these cases it makes a huge difference.

But this can differ when you are on old hardware, consoles or mobile devices. I am still learning with our latest projects how they behave.

Baking can make a difference if done right. But it always comes with higher memory needed for all the baked maps. So you need good asset management, maybe streaming and a good memory manager.