I'm not saying that we shouldn't make the tweaks in our garden that we think produce the best flowers, it's just that tweaking something like lighting from, as you said, the tried and true super HPS has probably negligible gains (if any) that would go unnoticed by the patients we grow for. For instance, missing a watering or two during flower can take herb from a hypothetical A+ to an A-. Dry a little too fast and skimp on the cure and now you're down to B/B+ territory. It doesn't take much to negatively change the quality. Now if you're already at A+ and you tweak lighting, who is going to notice a difference? If you're growing B+ herb and you change your lighting, who cares, right? Your herb still sucks, lol.
Sometimes it's hard to judge our own though because like you I make lots of tweaks that I *think* make a difference but I have yet to hear a comment about how 'something was better this time'. We're too close, unsolicited feedback on an increase in quality is what I'm talking about here.