I have damn near zero relief in my necks; they simply feel better to me that way. I also set my pickups significantly lower than factory spec; they simply sound better to me that way. Like you said, no right or wrong and there's a reason things are adjustable. There has to be a baseline in manufacturing, a goldilocks adjustment that can be used as a reference point to crank the product out the door, but from there its all what works for the user.
For sure, once the power tubes start taking a bigger role at higher volumes the whole nature of the sound changes for me so I have to tweak the EQ. Same deal, I need to hear what I want coming out of the amp and monitors. Don't care too much what they do FOH after that.
The actual published Fender/Gibson spec is .008" to .012" and I generally shoot for the middle at .010", which isn't much relief at all.
The guitars play very well at that spec, so I see no reason to alter it, although some do, and that's fine.production., scientific reason for relief is to ensure there is no fret buzz, especially when the strings are struck very hard and they begin to oscillate.
I am amazed at how much musicians complicate things, but I guess when it's not your living, you can dick around all you want.
Every time someone tweaks an EQ in a club I have to laugh because it's an indiscernible difference, but they've conditioned themselves to believe it. We've sat and listened to the playback and the waveform and I literally laugh outoud when the guitarist is faced with the reality that his tone did not change..and some guys get pissed when their theory is dispelled.
But, the industry is constantly telling people myths like these tone caps have a warmer tone, or this wood will give you this or that and this musical mythogy is big business.
Spending the past 7 years working daily in the professional recording industry dispelled many myths I had learned about sound production.
I was working at Capitol one day as part of a team and this guitarist kept moving his mic and dicking with his EQ's and the producer punched in and said "Get this guy the f***k outta here and get me someone who can play the guitar and not just twist knobs. We are burning $300 an hour here, Sport. Strike 3, you're out..."
My job as a music instructor is teaching live performance techniques. One of the things we teach the students is not to fool with changing settings and focus on the performance.
Efficiency and economy of movement are vital to earning a living in this industry. When a Grammy nominated producer tells me something, I don't try to outsmart him/her or present my personal theories, I just do what I'm asked and I remember the experience...but that attitude is what's kept me steadily emoyed and in demand.
I've learned a lot from these guys. Simplicity and repeatability is king.