I see you point and I agree that would be a better solution in most cases but I will be filtering each channel so I can really mix the channels to increase intensity.
My choice to use 3 leds was to avoid realizing at a later stage that 2 leds did not create sufficient illumination, In all honesty I think two would be enough but I would rather be safe than sorry.
My priority is really that the the light output is high, and that I have 2 channels that are neatly balanced (location wise), but I guess things are a bit flexible.