A tweak is just a change of small magnitude compared to other more major changes that all together in the end determine how things sound.
The effects of tweaks are cumulative though. Some may have good synergy and improve things, others may have a negative effect, the effect of others may be too small to notice.
All that matters is that in the end your system is tuned to your tastes. Tweaks can help get you there. But if things are out of whack to start with in a big way, minor tweaks may be of little consequence. Get the big things right first, like the room/speaker/amp combo, then tweak away from there to fine tune things if needed.
The effects of tweaks are cumulative though. Some may have good synergy and improve things, others may have a negative effect, the effect of others may be too small to notice.
All that matters is that in the end your system is tuned to your tastes. Tweaks can help get you there. But if things are out of whack to start with in a big way, minor tweaks may be of little consequence. Get the big things right first, like the room/speaker/amp combo, then tweak away from there to fine tune things if needed.