There is a YouTube pose on here..
someone skipped a release, waited for the app to re-announce the next one and it was 2018.24.1 and not the skipped 2018.21.9 and it installed without issue.
So it appears it installs what is needed to update your image (at least from that one sample lol).
And of course from that you see they are not differential software patches and you don’t need them all.
If you can stand to ignore the ‘yellow clock’, wait for the app to tell you about the next one and go ahead and load that one.
NOTE that the SC will/might re-trigger a reload of the current one so don’t trust a notification from a visit to the Service Center as a ‘new’ version. All they do is trigger a download of the ‘current’ version whatever it is.