Why are passport processing timelines so different?

Just out of curiosity, looking on the British Passport application processing timelines thread, it seems that some people have their passport application approved in a couple of days while others wait a month or more

The ones I looked at are all first adult passports after naturalisation.

I guess it’s nothing urgent but my anxiety would be a lot better if I knew how long it’s likely to take and when my documents are likely to be returned

There's no "official" explanation for this, except perhaps the pandemic and varying workloads at different offices, rush times towards main travel periods(?). HMPO won't give any special advice on this unless circumstances force them to.

https://www.gov.uk/renew-adult-passport ... 20passport.