There's a lot, I say, A LOT of techy stuff that some use to gain an extra gram or two. In 15 years of growing, guess I've tried most back when I had larger grows and could prove or dis-prove some of the more popular ones. I usually would test "theories" by growing 3-4 of the same strains with one as control and 2-3 to do all the shit to. I musta had a bunch more energy then to waste....
To be honest, I never saw a gain significant enough from any trick that was any better than doing the basics of care to maintain health of the plant. Anything else falls into the "pushing the rope".
The best of the "tricks" are to digest all the knowledge you can from all the places you can...collate into usable methods with plant health as your guide.
On flushing. I don't as I'm organic.
I always have a photo alongside my autos but never tried reducing lighting....when you're running a marathon, why reduce what could be a last surge? Doesn't seem logical.