Most of those routines that advertise 5 days a week thing are using a little something to speed recovery. If your not getting sore, even a little, then your probably overtraining or not pushing hard. I used to do that and always used to say "I'm never sore!!" and was proud of that. Then I cut back my workouts by alot, I'm sore for a few days afterwards, but I also set personal bests in all my lifts and noticed huge gains.