You don't...It was an example and I think you know that. The OP's light is 260w. Besides that, it's not about wattage at all, it's about ppfd or par at the canopy. At full blast his light tests at 290umol/s in only a 1'x1' square at 24" and about 150umol/s in a 2x2...Since when do you need 600w for a seedling or up to 3 to 4 weeks in veg?
300w of mostly blue spectrum has worked very nicely for me.
Why the hell would you turn any part of that light down?
My point, and I'm sure you understand is that why would you kill the ppfd numbers by turning half the light off in an attempt to shorten node space? The 2 are opposite of each other. Keep the light at 100% in full spectrum, provide more photons=faster growth and shorter node spacing than blue only because we are twice or more the par levels.
2 things shorten node space right? Strong light and blue spectrum.....Strong full spectrum will win every time over 1/2 power light in blue spectrum.
I think you know these things and get the picture, you just like to be combative at times if anyone says anything contrary to your "wisdom". I'm good with that too but after 50 or 100 cycles striving to grow big dense, tight plants I know what has given me the results.
If lowering par levels to a lettuce grow level works for you that's great and I'm happy for ya!
Now, if the OP had a 1200 actual watt light that has the same adjustments then yes, turn the red down because you can still provide huge amounts of par with blue because you have so much more power on each side of the light. But with only a 260w light I would never run it at 100-130 watts in mostly blue thinking it's going to make internode spacing tighter than if I run the whole light. Not going to happen with that setup. Sorry sir.
Blue equals more leafy finish too. No thanks. Oh, and red spectrum photons carry more energy than blue.