I passed my RHCoE in Ansible Automation yesterday with a 286/300. It was much easier than I expected, covering only pretty basic scenarios in my opinion. (I'm not sure what I missed, since I tested everything before I left. Some questions were worded rather vaguely, so potentially a misunderstanding.)
My preparation was a little bit unorthodox. I took three Linux Academy courses: the quick start, Using Ansible for Configuration Management and Deployments, and the certification prep course. Combined, these formed a very solid, well-rounded basis in using and configuring Ansible. I do not have much hands-on experience from using it at my job, since we use Puppet for most configuration management. However, I found a bug in an Ansible module one day and decided to try to fix it upstream. My pull request was merged that evening, and I spent the next two or three weeks working on bug fixes on GitHub and diving into the Python code that runs Ansible -- as well as providing support on issues that turned out not to be bugs. Since Ansible is an open-source project, anyone with a Python background can benefit from contributing to it. It's probably overkill and unnecessary for most examinees, but for me it was a great substitute for my lack of hands-on work experience using Ansible. And of course, the courses here prepared me enough to know what I was doing in contributing.
I'll try to answer questions, but I have to remain pretty tight-lipped due to the NDA.