You're right, a lot of things can happen but as I stated before it's on a person to person criteria.
My entire family lives in the US so I wouldn't have any need whatsoever to come back here after my arrival in the US. The USCIS estimate is based on a 80% over a span of 6 months. USCIS hired over 3000 employees in January and has since started processing cases not on a month to month basis but on a 40-50% done move to next month basis. This means that the spread among 4-5 months of processing has rendered their estimate system in place on their website useless.
I am unsure if It's allowed to post external links here but here is a link to an excel spreadsheet we keep on "view only" mode for the mass public by data scraping case tracker every single day for changes in cases. We have exact dates on when cases were submitted, received, RFEd, and even Approved so we can accurately tell what the processing times are right now. Which is somewhere in the neighborhood of 13 months/14 months and dropping. The months of January and February specifically have way less cases than the rest of the year so in a matter of about 1-2 weeks USCIS will begin working on March/April 2022.
https://docs.google.com/spreadsheets/d/1sN2bo1xZhs8oVU6-QDUdBXBX2_ci8_QJ0wiz59Gp6H4/edit?fbclid=IwAR0_dTQNIXl44Yc08XXDS-bLN6dXYcDAqEsHm2XpU1n9XngKSAnRaRSSDmU#gid=1603169151
Anyone interested just take a look at said link and save it for yourself to keep yourself posted.
USCIS at current speed is completing nearly 5000 cases per month right now, with last week being somewhere in the neighborhood of 1200+ and this week possibly reaching that or exceeding it as well.
I'm a data guy so I love keeping track of this kind of stuck and helping to provide accurate numbers.