Most Helpful Guy
The idea of trimming it every couple of months is meant to get rid of split ends. If you NEVER get split ends, then trimming it is unnecessary. People give that particular advice because pretty much EVERYBODY gets split ends every now and then.
So I guess the fastest way to grow out your hair is to avoid trimming it as much as possible, which means avoiding split ends as much as possible. In other words, if you work hard to prevent split ends, you won't have to trim it; and if you don't have to trim it, it will grow faster.
Most Helpful Girl
Time and patience. Hair only grows for most people in good health, 1/2 an inch a month. Growth depends on your nutrition, how often you are cutting/trimming, and if you have healthy hair/scalp that will help promote growth to begin with.
How can you get say 6 inches more of hair growth if you are trimming an inch off every month? It's counterintuitive to hair growth to keep relentlessly cutting/trimming your hair. Trim if you have verifiable split ends, and NOT because a magazine or a hair dresser says you "need" to cut your hair.