I agree. If you already know how an equalizer functions, then it's simply a trial/error method. The reason it can't be anymore specific is because of the vast recording possibilities: room ambiance, microphone, guitar set-up... Even if you are recording directly into a PC, there's type of guitar, action, string weight, tone, your style of playing vs. style of music, accompanying instrumentation and their levels...
I could go on and on. That's what makes recording such a fascinating and rewarding process. Every session is different, and there are so many perimeters to confront!