alt Hacker NewsMobile GPUs use tile-based rendering. A long thin triangle touches more tiles, so it costs more. That could make you think you need to use Delaunay all the time. But the gain from nicer Delaunay triangles on the GPU is small relative to the time you pay for Delaunay on the CPU. I've measured time profiles on map data. It could be that for games it pays off.
Definitely, you have to understand where your bottlenecks are. That's why it's best just to author good models.
Nanite/triangulation can help relieve GPU bottlenecks but if you're already stomping your CPU it won't help. Whether it's a good fit depends on your workload.