What color is the car? Dark colors will need the finishing step. Light colors like silver, white, gold, and the like won't "need" it. It won't hurt the paint's look, though, if you finish down on a lighter color. I wouldn't simply because I get tired.
I've finished down on lighter cars with Intensive with no ill-effects. If you have good technique and really work it down, you can go straight from IP to LSP on some cars, but the blanket policy is generally to finish down with a lighter polish.