Most satisfying was reducing the time my ci/cd did to build,test,verify complance and deploy of virtually anything i want in lrss then 10 minutes. From code to running appliance fully configured and being absolute certain it will work without any other modificatio . it used to be an hour.
Achieved this to do lots of caching and parallell test runs.
The downside is that my development server is feeling like a unvoluntary black person from ghana moving to the newfound united states 400 years ago...