Im thinking for auto plant lighting.
I would start from seed with full power 20/4 with a 32k full spectrum light sources until the 3 week of flowering or until the end of the stretch. Then flip the light to 40k or 42k more white full spectrum. And then add some deep blue for 3 to 6 hour's a day for the last 2 week's before harvesting.
Just thinking out loud... But this mite be a good starting point. ?
Dunno mate, your guess may be as good as mine.
FWIW, my approach in future will be to start seedlings on 24/0 until at least a couple sets of real leaves are out, then ramp over to 20/4 for the rest of the grow.
As to spectrum, with my screw ins, all my plants have tended to the squat side when I biased spectrum toward the 5500K bulbs, so I am beginning to think that they need more red early to stretch a bit more. In the last two grows, I have used mostly the 5500K bulbs until flowering, and then for flowering ramped over to mostly 2700K which have a lot more red. In future grows, I may start out ~50/50 of the two spectra, and then finish off with more of the 2700K during flowering. In the last grow, I added UVB bulbs for the last couple weeks. No idea whether it made any difference, but it may have, and there is room for the extra bulbs, so I will continue to add the UV in late flowering unless my information changes. I don't fuss with extra red, the 2700K bulbs have lots of it.
I now have a par meter, so I will be setting up to do DLI somewhere in the neighborhood of 45-60 mols/m2/d
Maybe you can interpret something useful from how I am using my screw ins, maybe not, but good luck with it either way.