Factorio is my all time favourite game. I am convinced that it has made me a better engineer. As a hiring manager, I have started accepting save files of well functioning factories to have applicants skip past the resume stage of the interview process.
Automate
Don't tear down the old version before you finish and test the new version.
Don't be afraid to waste resources if it lets you save time
Temporarily speeding things up manually can only help with latency, not throughput
Perfect is the enemy of the good
OCD will not help you, don't worry about your belts being laid out correctly