Like most everything in poker the answer to this depends on lots of information. Size of the blinds and antes, stack sizes, player tendencies, action in front of you, potential action behind, your precieved image, skill level of your opponents, your skill level, position on the table and stage of the tournament if that's what your playing just to name a few. Did you have a particular example you wanted to go over?
Trying to quantify a very general answer I would say it is a move that should be utilized when the amount of $ you stand to win is significant in comparison to your stack. Some say increasing your stack by 10-25% is worth while, but again I think this depends on many factors.
I vaguely remember reading a story some time ago about an individual (amateur player) that from the very beginning of a tournament was given a list of hands (AA, KK,AK and maybe QQ if memory serves me right) and they were told when you see these hands go all in, otherwise fold. Supposedly they made the final table of this MTT and the only reason they busted out was they deviated from the plan and called with one of these hands. In turn leading to a out draw and bust. Obviously this individual was on the right side of luck for this to work as well as it did but the preflop all-in is a strong play and can help level the playing field against tough competition as in this example.