Yeah of course! Always happy to answer questions.
For an atlas, yeah he’s pretty much correct. The only thing limiting the number of textures within an atlas is their texel density. Again though, it is important to be smart about your atlasing. If you’re atlasing a texture that only appears in one room and another texture that only appears in another, then these two objects will never be on screen at the same time and thus you are wasting space.
If you are committed to atlasing a lot of textures and your materials are relatively simple, then I would suggest you consider switching to virtual texturing. This will allow your atlases to be unconstrained by the normal 8192 limit (though I would still be smart about it) and does a much better job at optimizing atlas space by only loading areas of the texture currently visible. It’s also great for memory optimization. The trade off is a hit to shader calculations, as each unique texture needs to be sampled twice now.