I'm no longer involved in the industry but my impression of modern signals is that there is a wide variation in what is acceptable under the current regime. From just after the inception of colour light signals up to the widespread adoption of LEDs there was a clearly defined and very tight specification of how the signal should look, light intensity, colour temperatures, beam spread angle etc. This meant that wherever you saw a signal the perspective you got was the same throughout the system, other than a small number of low speed instances fitted with 'Spreadlite' 20 degree beam lenses. Today it seems that anything goes as long as it is approximately red, yellow and green, doesn't show up very well from a distance in daylight and dazzles at night when close up.