The first impulse on seeing a photograph on an HDR monitor is to find the brightest part. That moment is enjoyable, but brief. A few seconds later the eye returns to the subject, the midtones and the direction of the light. If those do not hold together, a higher highlight peak will not make the picture better.
That is why Acutance Studio maintains two development profiles. The SDR profile is not a dim miniature of the HDR version. It is the photograph many people will see on their screens and in their software, so it must stand on its own. HDR has room for more light, but need not rewrite the scene.
Consider droplets on a flower. In SDR they need shape, transparency and context. In HDR, a few droplets can carry a point of light closer to the feeling of the original scene. If achieving that point costs the texture of the petals, it was a poor trade.
The gain map connects the two interpretations inside an Ultra HDR JPEG. An older device shows the SDR base; a compatible viewer and display use the map to expand the rendition. Greg Benz explains the relationship with clear examples.
Our favourite test is simple: look at the photograph, press H in Photo-View, and ask what changed. If attention stays with the subject and the light feels more faithful, HDR is doing its job. If the effect itself dominates, return to the edit.