John. What myth are you busting?
The DLI is the area under a curve. You can find area by superposition, the calculation is linear.
Therefore, one can increase the dark period to any length as long as one accounts for the DLI loss in the day time. In theory, a 0.0000000000000000000000001 second burst with the entire DLI for the day, then dark for the remainder of the 24 hour cycle would be the fastest flowering of a strain you could do.
This is science that is well known and in text books. It might be somewhat novel to the homegrowing folks, but it is established science.
Nobody has taken this to the secondary metabolite ratio level, but we do know that there is a negligible amount of yield loss when accounting for DLI (aka no negative impact) with the amazing positive of finishing weeks early.