It's hard to really articulate what the parameters are that make one song parody-able and another song not, but if I can come up with a good enough idea for it, I go for it, and if not, then I have to move on.
I'll bet every great thinker and leader we've got
Could see all kinds of things other people could not!
So then why get upset if somebody like me
Tries to look at the world just a bit differently?
I'd like to be able to be more topical and timely and more of-the-moment and I think the way to do that is, instead of waiting until I have twelve songs to release all at once, just to release them as I come up with them.
In fact, when I come up with an idea for a parody I try to resist the urge to Google the idea to see if someone has done it already because the answer is almost always, "Yes, of course they have, they've thought of it!"