I actually really believe in this. Soon I want to conduct an experiment regarding willpower with Lucid Dreaming. Very few, if at all anyone, has ever tried LDing off of pure willpower and no practice. I believe that it is possible, but in order for that to be so we have to destroy all of those mental blocks and schemas preventing us from attaining LDs at will.
To an extent I really also agree with Seltiez. I think its really good to get the hang of it at first, then after a while you can create your own, easier way to Lucid Dream. From past experiences I would say that pure belief, or better yet "knowing" that you are going to LD works, but only to an extent. I haven't found much evidence that suggests you can get Lucid Dreams with no practice, and trust me, I was really hoping too, but then again I still havent conducted a solid experiment on it.
If you want consistent and frequent LD's then you'll have to go to techniques/methods for that, at least thats what I've learned from my experience so far.