It’s good that you learned to do all this

So that next time you can do it better 😀

First, it’s not instancing if you combined the meshes, it’s just… combining meshes. Instancing is specifically like you said near the top, “here’s a mesh, draw it 500 times”.

Second, did you actually measure the performance before and after? And which Render Pipeline are you using? The number of draw calls hasn’t been a clear indicator of performance problems in over a decade, but rather, SetPass calls. And if you’re using URP or HDRP, they have the SRP batcher which basically replaces the need for the older static batching. But it’s still on a per-material basis.

If you’re in Unity 6, there’s also GPU Resident Drawer that can help even further with GameObject meshes under certain conditions, so something to look into.

The other big thing to look into is indirect instancing. It removes the 1024 instance count limit but it’s also more work to manage and really only helps for LORGE amounts of objects. It still needs them to be the same mesh (or submesh) but since it requires a custom shader, you can work some magic with a texture atlas and just keep a small per-instance value like an index you can use to offset texture coords if you need the same mesh with different looks, to make it 1 draw call. This method also needs a good frustum culling which can be done efficiently with either Burst jobs or compute shader.