If you are having those issues with booting maybe it is because you configured your network share incorrectly? If you are waiting on shutdown timeouts for something then just go edit the timeout. systemctl edit <stuck thing>.

Typically when I crawl through journald it is to diagnose a problem with a specific application. Actually, the fact that those logs are easily accessible in a centralized place with easy to understand commands to access them is a reason why systemd (or more specifically systemd-journald) is so great.

The only times that I have had major issues like that was either because (A) I misconfigured something or (B) a package came misconfigured.