Hmm, I personally have muscle soreness more than muscle achiness. Not sure if that's the same thing you're describing.
I'm not doing parkour-specific workouts all the time, but I do pushups, sideups, v-ups, squats, situps, padwork drills, sparring, etc... 3-4x a week. And yes, I'm in a constant state of sore

I remember I took 2 weeks off from working out a while back, and realized that nothing was hurting for the first time in months. It was such a strange feeling! :p