I know in the incremental article, it specifically states that going from 10.15.1 to 10.19 doesn't require any incrementals, but when I tried it on my server I ended up getting an error during startup/db updates that halted my upgrade. It was where the upgrade script could not find a column for certificate expirations.
I ended up rolling it back to 10.15.1, upgraded to 10.16.0, then 10.16.1, and finally up to 10.18.0. I still had to rename a few tables manually, but my error finding 'pending_revoke_certificate' column was cleared out and the upgrade went fine. Not saying it could happen to your instance, but since my db has been upgraded a few times starting with 9.91, it's worth keeping an eye on on the log.
