You're asking the right questions, but they are some of the most complex topics in Windows, and I'm not always sure how to make it easy to digest, so please bear with me if it's too long or not as direct as you may have hoped for, such as a checklist.
Something like this is mostly based on hands-on experience, because we have to know how things are intended to function before we can know if it's bugged. This means doing hundreds or thousands of hours of researching documentation and manually experimenting, to learn how things work under the hood, and to establish a familiar baseline to compare against when we tweak things.
If there was an easy way to find all the bugs, Microsoft would do it and we wouldn't have threads like these. That's why quality control teams exist, to manually bug-hunt in different ways. Nowadays though, the customers are the testers, because it's cheaper to release alpha products and let customers finish the project for the developer, and sadly that has become standard practice.
Take a look at this thread (
link1) for example, where I discovered the 22H2 task scheduler bug. I found it by just doing hands-on testing. I notice all sorts of bugs and typos like this, and report them using the Feedback Hub when I come across them. I found typos in the power plans, a memory leak in the Windows Mail app, I got the Nvidia/Windows DPC bug (
link2) acknowledged, and plenty of other things.
I'm not sure how to better explain my methods, other than to direct people to the Gaming Lounge (
link3), and urge them to go through every guide and do all the steps, regardless if someone needs or agrees with the tweaks, because the whole point of that exercise would be for it to act as a Windows training camp that would give someone years of skills and knowledge in a one or two week period, which took me 30 years of learning the hard way. After that, people can springboard off those guides and continue with their own research and tweaking.