Brightness figures on a datasheet are measured in conditions your showroom will never see.
When a display underperforms after installation, the cause is almost always ambient light that was never measured. A panel rated for a dim meeting room will look washed out behind glazing, and no calibration recovers it.
We survey ambient light and viewing angles before specifying anything. It adds a visit to the process and removes the most common reason a display estate disappoints after handover.