New style of work-out

The runners I have met here seem to incorporate, as a staple in their training program, a type of work-out I have never done before and it is really growing on me. My training week typically consists of 1 session of aerobic intervals, 1 session of threshold intervals or a tempo run, 1 long run and then runs to fill in whatever my mileage goal is for the week. Pretty standard. My running companions here have added a twist to the tempo run. First, they run 8 km slightly slower than 1/2 marathon pace (only a couple of seconds slower) then without stopping, they run 2-3 more km as fast as possible. I LOVE it! First, it keeps my tempo run honest as normally I tend to run too fast during my tempo runs and then am burnt for either my long run or aerobic intervals. Second, it teaches the legs to turn-over quickly when they are already tired i.e. exactly what one needs at the end of a race. I will be incorporating this into my training plan from now on.