That is one truly excellent guide to practical log usage and analysis. How come I've never come across that site before? Thanks for the link, it's much appreciated!
The guide was probably written prior to the introduction of systemd, and focuses solely on the standard syslog-related tools, logrotate, cron, and various handy GNU tools for parsing log files and extracting specific information. As long as one is running syslogd or one of its relatives, everything in the guide is still relevant to a systemd-based distribution.
(If anybody wonders what all the noise is about regarding binary systemd logs vs. the syslog standard, they might want to take a look at this guide and consider what we'll lose should syslog no longer be the standard mechanism for logging on Linux in the future.)