That's a pretty tough assignment for anybody. It's certainly OK for training as a 1xwk workout, but I wouldn't put much faith in that or any similar workouts as "indicators" of 3200 or 5k race times. Too many variables related to basic ability, mentality in racing, and just plain unknowns. Trying to turn numbers into predictions, especially with so many variables in racing just never worked for me beyond some very general fitness and experience elements.
Any variety in intervals together with distance and hill running and fartleck and "chases" and flat out 200s to 800s with repetitions will all work, when the consistency and work ethic is there.
It's like the difference between practicing a musical instrument, doing exercises, scales, and flexibilities and "chop" building: one of your promising horn players can be a real terror in the practice room, just flying through everything he's working on, and then, when it comes to the performance or gig he might falter, choke, or just not have the stuff the more talented kids have. Sometimes it's "head," sometimes "heart," and sometimes genes.
Do the basics as you know them and give the kids an enjoyable experience when it comes to workouts AND racing. Don't try to count angels on the head of a pin.