Practical Programming has suggestions for when to include those. But if it ain't broke, I wouldn't try to fix it (i.e. if you're still making fine progress doing things the way that you have been). Then again, adding chins or lower back work might not hurt your progress either. At any rate, you're going to have plenty of questions like this, so purchasing PP isn't a bad idea. Nor is visiting a few of the sites that we name drop around here occassionally.
-Stacey