I use automation quite a lot. Even when not doing silly AARs with diplomacy on auto.
Ship Design, troops, taxes, construction ships, explorers, the odd military single ship either very early or when I get too rich for my own good. Those are easily put on auto.
Manual taxes is not a lot of work, but you need to pay attention with alien populations and war, and when conquering alien colonies in particular. When starting war, your big, nice cash cow of an alien colony can rebel forcefully in a moment if you don't pay attention. Basically tax big, colonies with good revenue until the smiley turns grey, and leave the rest at 0. This improves the empire quite a lot, and that is not always wanted in my games. Better population growth, basically the same taxes as the AI.
For troop recruitment it can be nice to hire a few extra manually when you need some more. And leave the main work to the AI.
I like to keep agents on suggest, or I forget to send them. I don't usually do what is suggested, though. I hire manually.
I hope that new Legends options in game setup will make it more interesting to optimize some things further. And I love that the game gives so many different ways to automate. I just wish running some parts (Looking at you - ship design) was easier to run on manual.