Let me say up front that I am not a mastering engineer.
I am a composer and sound developer.
I try every tool I have and tweak it to find new sounds.
Finalizing everything form tiny samples that last a tenth of a second to my own epic pieces.
I have learned a few things, Human Ears are good (hopefully), but get fatigue.
Computers and software do not. Not the fact that i rely on my hearing, i do use software like AAMS to control and the analyzers / charts to view what is happening.
My eyes and ears i use now!
To me this gives me a greater and better understanding of mixing and mastering.
And i do jobs faster and do not get so tired!

Francisco Javier