Just how long does my drill have to be?

I've taken a few minutes break here, to both put together a short blog post AND to give me a break from content creation and Keyword research duties!
Earlier this afternoon, I started re-jigging some content that I'd already created, to make it more suitable for a particular website that I'm in the early stages of building (I'm still just creating content actually).
As I was altering the text, I kept seeing the phrases I'd just written as possible Keyword phrases and so, from time to time, I'd plug one into Jaaxy and see what I got back. Up to yet, I have over 200 various phrases, most of which have a reasonable set of Metrics to back them up.
But having that many Keyword phrases got me thinking; I know they say that you should drill down into your Keyword lists, but I wonder, how long does your drill need to be? Do I stop now? Do I continue as I am - plugging in phrases as I create them? Or do I admit that I'm becoming obsessed with Keyword drilling - and seek professional help? :-)
Well, only a short one today - yes you've guessed it, I'm dead keen to get back to my Keyword drilling! :-)
If anyone has any ideas regarding this new affliction of mine - and how (if?) I should try to put some form of control on it, I'd be much obliged to hear from them! :-)