I usually go 8-10.  I had a friend who went 6 months, though.  Not sure how she managed that.

My hair is texturized. I only get a re-touch every 6 months.

The texturized hair and the natural hair is so close in texture, that it's hard to see where the new growth is. I can feel it when I touch/comb it, but it's hard to see with the naked eye.

My hair was all natural up until it hit shoulder length, so the "nappiness" of it isn't a big deal to me. I love my natural hair (which is the reason I had it texturized instead of straight relaxed), but the longer it got, I couldn't handle it.

This is a very happy medium, I can have "big" hairstyles, where my hair in a faux afro, and still easily blow dry it if I want it straight. Also, I can have it re-touched twice a year, instead of every other month.

I've had straight hair before, and I hated it. It's the big reason I've had my head buzzed so many times. My natural hair would get very long, I couldn't handle it so I'd relax it. I'd hate the texture of it, so 7 to 8 months later, I'd buzz it.

With a texturizer, I can let it grow and not go through that grow/cut cycle anymore. I LOVE IT and would recommend it to everyone.

Edit to add: Also, if I want it completely natural again, I don't have to cut off all of my hair again. It will be easier to grow the chemical off and have it trimmed every few weeks than if my hair was straight, due to the similar textures.

New growth WILL NOT break off your hair. If anything, it's much stronger than your relaxed hair. When your hair is "shortening", it's usually breaking off at the ENDS.