why the producer's answer is 'it depends'

Introduction  to the subjective nature of music methodology

I've said it before and I'll say it again. Music is an artform, Audio is a science. The two joined together create the magic that is a great record. Certain things are subjective, others are concrete. There are principles behind audio production that can help you to get a better sound on your recording, but the application of these principles will almost never be a 'one size fits all' approach.

project goals - the ideal sound

So your song is structured out. You've got your go-to tone. that's great. You've imagined your ideal sound and that's probably the hardest part. Now we get into the tricky bit... Laying it down in such a way that the end product matches your initial vision.

I remember my first dozens of songs. I would set out with the intention to make a Punk song or a Dub song, but somehow it didn't turn out the way I planned it to. Why? was it lack of experience? Was it lack of the correct tools or my inability to use them? I may never know. Sometimes the unexpected can be a real treat, sometimes it's just a disappointment. 

a myriad of tools

In our modern digital age, we've got a nearly unlimited variety of tools to choose from. For example, what kind of microphone is best for a male vocal? answer, It depends on the singer, his pitch, his Timbre (the tone of voice,) the positioning, and the room. 

how do I get a thick-heavy tone from my guitar? it depends on a lot of things, what kind of pickups are in your guitar? what amplifier are you using? settings on a pedal-board? are you using a DI (direct signal?) are you prepared to re-amp your guitar later? do you have the ability to add thickening in the mix?

The same applies to EQ settings. A lot of time, there will be a range that you can approximate where an instrument falls, assuming you're mixing a rock band. Is it the same for classical music? jazz? the answer is it depends.