I had pretty red color at low light actually, which is not what many would assume.

The tank had few fish and relatively low NO3, I add more and did not get much color change response.

At low light, the plants does not stunt nearly as much and is able to survive pretty well.

Folks that like lean nutrients are wise to use lower light to balance their lower nutrients...........

Higher light to balance with higher nutrients/CO2.

As long as you are adding a good match at the right time, there's no reason adding CO2 only at the high light peroid will not work.
It should in theory and apparently in practice for you.

But...........what would make the method you use even more stable and robust?
What have you learned from high lighting?

Good stable CO2, good stable nutrients, routines like water changes and cleaning/trimming, good current etc.............

When you apply those same methods to a low light tank, now they are not as critical, but they still offer and wider range of stability: much more wiggle room with respect to dosing, targeting a range, less algae etc

Which most every one says they desire..................I do not know anyone that does not desire that goal.

There's a lower end to that to be sure, but it's a lot lower than many give it credit for.

Regards,
Tom Barr