Brent Ozar provides a reminder:
Even if you can knock out one of these per month on every 2017 & prior instance that you have, you’re still gonna be banging up against the October 12, 2027 deadline.
It’s not like your servers will magically stop working on that date – but if your company’s insurance or compliance rules say you’re not allowed to run out-of-date software, then it might be your butt on the line for not getting onto a supported version. (And if you’re subject to that, and you’re still running on SQL Server 2016, I’d be curious to hear in the comments how your experience went trying to purchase 2016 Extended Security Updates (ESU) from Microsoft.)
Brent has a list, and if you have any 2017 instances kicking, it’d be a good idea to get started on these.