My dd went through a phase where she almost never nursed except naptime and bedtime unless I offered. This was right around 12-14 mos or so. She also learned to walk during that time and was just too busy. I offered throughout the day, because I didn't want her to wean, and she wasn't drinking really anything but my milk. Now, at 22 mos, she asks all the time, so I don't offer very much any more. Now, I only tend to offer if I sense an impending meltdown, or she needs distracting from something else. Not offering hasn't affected her nursing frequency really at all - she's still nursing quite a lot. This isn't so much a technique I'm using though, just that it doesn't come up much since she is quite verbal and can let me know what she wants. And since she's nursing 6-8 times in 24 hours still, I'm not worried about her not nursing enough!