Critical Velocity Workouts in a 2 week microcycle

[westharrier]

CRITICAL VELOCITY

I am very interested in weaving this pace which I believe is about 90% VO2max pace into our cross country workout plan
for next fall. I used it on a limited basis with some 8th grade milers this spring and they thought it was to easy. They were
fairly high achieving guys all around 5 minutes for the mile. We usually ran 400's at CV pace while jogging a 200M between each one.
I never had these boys run more than 6 of these just to get the feel of the pace. We usually followed them up with 3x 200M at
mile race pace also with a 200M jog. My main question is HOW OFTEN SHOULD THESE CV workouts be put into will say a 2 week
microcycle throughout the cross country season. When these workouts go in obviously something like LT work or VO2Max work
will have to be pushed aside that day. Thanks for any light you can shed on this.