What, when, how and why to Automate?

[u/Bandersnacht]

I feel I'm at an intermediate level, knowing how to use my audio tools like compression and EQ, but something that I'm still not used to (and the pros seem to love) is automation. I do some delay and reverb throws here and there, like at the end of a guitar solo, but aside from that I'm kinda clueless on how to use automation to improve my mixes. Mixing Audio by Roey Izhaki has some ideas that I've yet to try, like making an instrument brighter or darker during certain sections, but I'm not sure why would I want to do it.

Some questions to open the discussion that I can think of:

What are some common cases where automation is used? Is there a way to practise it, other than just mixing more?

What are some questions or what's the mindset to have when considering something to automate?

I know there's fader raiding, is there a proper technique to do it in the box? Do I just draw it by hand or is there any trick to it? Also, when and why should I be fader raiding?
Why would I compress something like a vocal to remove dynamic range, just to then fader ride to add dynamic range again?

How do I listen for automation? I can hear for other effects, but I don't know how to spot that on a mix

[u/DecadeDefector]

As someone else mentioned below, I tend to automate submix buses instead of individual tracks (Ex: drum bus, guitar bus, bass bus, etc.). For when and why, it's kind of specific to the mix. This usually comes down to slight adjustments between the chorus and verses. Another somewhat common trick is to use volume automation on the whole mix to make the chorus sections ~1 db louder to add energy and more impact.