I'm agin it, personally. I'm a big believer in pushing as hard as you can, as often as you can, working at the edge of your ability, grabbing for things that hover out of reach. A man's reach should exceed his grasp, and all that. In fact, I'm a proponent of only using your best ideas. There's enough mediocre fiction in the world.
Besides, how else do you find out how far you can reach, unless you are stretching outside your comfort zone? Every book I've ever written, more or less, was a book I didn't yet feel capable of writing.
Another thing is that hopefully, as you use up old ideas, new ideas will grow to take their place. And it's my experience, at least, that ideas get cooler as you build on old ideas.
Which is not, you know, to say that I'm for writing things before they are ripe. They certainly need cooking time. (For some writers--truepenny, frex--a lot of that cooking time is on the page. For me, it's in my head. I've got to let the subconscious do the work before I sit down to write.
But the other way is valid too, and don't let anybody tell you it's not. It's like the old don't-tell-people-your-ideas bugaboo. That totally doesn't work for me. I have a hell of a time writing unless I can tell people my ideas, and keeping my cards close to my chest just gets me stuck. I need to hothouse them with other plants to get them to bloom.
Man, I need a nap already. *g* stillsostrange is younger'n me.