Why can a mixture of incandescent and fluorescent lighting improve color accuracy in a room?

Combining incandescent and fluorescent lighting can improve color accuracy because each light source compensates for the spectral limitations of the other.1

Incandescent lamps produce light through the heating of a metallic filament, resulting in a spectrum that contains all colors, though it is somewhat redder than natural daylight. In contrast, fluorescent lamps rely on the fluorescence of a phosphor coating to emit light, which creates an uneven spectrum that can cause colors to appear distorted. By mixing these two types of lighting, the resulting illumination achieves a more balanced spectrum, which helps to render colors more accurately than either source might achieve on its own.21