Sometimes I see messages that cause a boot delay but because of the speed of my computer, they still don't cause a major delay. However, when I look at boot.log (/var/log/boot.log), I find that not all the information that appears during the startup sequence is logged in boot.log. The information is in syslog. An example is
[drm] RC6 on
which I notice causes a hesitation. But it doesn't show up in boot.log. Now I am not concerned about that particular message but I am concerned that boot.log doesn't show everything displayed. Because of the speed, it is often difficult to read the exact info on the screen and thus search in syslog for it whereas if it were in boot.log, I would only need to look for words I recognize that occur around it to find what the exact message was and therefore to know whether it is important enough to further check on it.