From what I understand, wood is much stronger being thicker than it is when wider, so you can have very narrow tips if they are thick enough. Also, it seems it would depend on what the wood is; softer or more dense.
This is mostly not from experience of my own, but I think tip overlays are mostly needed when wood is softer or more brittle like the ERC I am working on because eventually the string might wear into the wood. Hope that helps. Doob.