Part of the reason why I like to grab settings "on the fly" is because you can then change those settings at runtime. By grabbing the setting only when I need it, I can tweak the configuration file while the script is running. For settings that can't be changed while running, I load them in at the beginning of the script and store them in scalars.

A genius writes code an idiot can understand, while an idiot writes code the compiler can't understand.