The defaults in Betaflight generally work very well, but I own and fly very different quads ranging from 2" to 6". It may easily be that there is room for little adjustments I can make with the tuning sliders in the Configurator. How can I use graphs and plots generated from blackbox data to determine whether the PID gains on a certain quad are excessive or too low or about okay? How do these scenarios manifest visually in Blackbox Viewer or other visualization tools?
This comes with an understanding of how the PID algorithm works and what it actually does. Bardwell videos can be good, but non-quadcopter reference on what a PID controller is will be the best way to visualize this.
Look at the individual P, I, D components, and see how they react to the gyros. A properly damped (critically damped) system is what you're aiming for. I don't remember the math, but you also can't just apply straight math to this, because some of it is by feel (looser = underdamped, tighter = overdamped).
Here's a photo stolen from quora (https://www.quora.com/What-are-over-damped-critically-and-under-damped-systems):