They are processed on a first-come first served basis. However, not all applications are the same. For some people, the background check is prolonged because of their countries of origin, maybe people with similar names, travel history, or any other delay. Imagine if they stopped processing every case as soon as they got to a "slow case", if they did that then nobody would get their applications processed in time. The application process is very complex and we don't know all the details of it, I don't personally believe there is any discrimination or favoritism.
This forum is useful to have an idea of the timelines, but it's also anxiety-inducing. Take a step back, and take It easy even if it's not the easiest thing. It's not worth it to cause so much anxiety on yourself over a process that you have absolutely no control over.
Also, for the people who are getting ghost updates, that's good. It means that officers are working on your case. If you haven't been asked for FP then you will probably be asked soon. FP asked for PR purposes do not carry over to Citizenship. I was asked for FP in both processes.