Let"s quote malmo first
"Let's say on your tempo run you've got four of you who are comfortable with 5:20 pace for five miles but you have two others who would have to struggle with that pace and another two who just simply are not in shape. No problem. The middle two could probably run for two miles, rest a lap and when the group comes around again, jump back in. Just as long as it's still a tempo run for them. Both the leaders and the runners jumping back in will benefit from each other. Those two out-of-shape runners? Jump in at the back of the pack for a lap or two, rest a lap, jump back in for another lap or two, and repeat until the run is over."
If you do the math, malmo believes an out of shape runner can do 6x800 at 2:40 with 80s rest. This is a workout for a 17 min 5k runner (15:30 runner if malmo wants them at tempo effort instead of vo2max).
I'm only bringing this up since SoM is supposed to be for "everyone", but there has to be scalability issues for people who are running 5ks 5-10 minutes slower than what even malmo considers an out of shape runner. Thoughts?