I have experimented with turning on use strict; and got frustrated at having to declare variables before use so ended up not bothering. It sort of slowed down the initial code development although, granted, it may well have speeded things up down the line had I persevered.
I used to feel the same way. It's true that not having to
think about variable scope or initialization seems easier
and faster at first, but those gains have costs like
difficulty of debugging and the constant danger of
undetected typos. Strict will help you think more about
why your variables exist and what constitutes sane defaults.
You will find yourself creating less variables and knowing
more about how your program works. The default values of
your variables then become very useful in determining the
flow of your code. Trust the monks, strict is your friend!