Sometimes you don't have the professional VO talent yet so you lay down a scratch track VO to rough the edit to. When doing long projects like this I've gotten into the habit of listening to the scratch track VO at 2x speed (Tap the L key twice) so running through them and cutting out the mistakes takes a lot less time.
And since it's a scratch track it's not terribly important or worth taking too much time on. For me (and likely for you) the scratch track is just a reference VO to get shots in order and very roughly timed in.
FCP has some pretty decent scrubbing abilities (Unlike Audacity…still) so use them to shorten some of the time spent with stuff like this.
Keep the script in front of you and follow along and you shouldn't have too much trouble keeping up at 2x speed; just remember to listen for long pauses (which will be shortened relatively), mistakes and all that fun stuff…like sneezes.