there are things that influence it a bit, but in the end it is primarily genetics...
a plant that cannot get dense won;t get dense if you use warmer lights or better control temperatures (higher temps cause larfier buds, but this is still relative to potential of genetics)
a stocky plant won't get tall just because you only use 2700K CCT light... even if more red has that effect in a statistically significant way.. it is not profound in this case.
it's good to know these relationships that effect phenotype observed, but in the end it is still primarily genetics. find a good one?
not sure what you want to do with 'flushing" i can tell you it does not change mineral content of buds, so don't do it for that false reasoning. do it if you wish, but find a better reason before you do. flushing is a great tool, when needed... like utter catastrophe in the root zone -- concnetration and/or pH so far off you can't make simple adjustments to fix it.. that's a great time to flush. flushing should be avoided... we do it when we've fucked something up.