Int. Tempo tends to end up being a cross between Special Endurance and Speed Endurance with respect to time worked, intensity, and recovery. 3 x 3 x 100 in 14s with 1 min in between reps and 5 between sets ends up being 3 x 300m in 42s with 7 minutes of total recovery in an int tempo session. A 6 x 150m speed end session in 18s with 6 min between reps is like a 3 x 300 in 36s with 12 minutes between, and a 3 x 300m special end session in 40s with 12-15 min rest. If you want to know why Hart's system of Tempo is good, it's because his int tempo sessions usually 6-10 reps provide a good link between speed endurance and event runs (special end) his athletes do. I would like to say his fall 20×200 and 16×200 sessions are demanding ext. tempo sessions which fall just outside of the Special Endurance 2 realm, but are too slow to be deemed intensive. All sessions of special, speed, and tempo endurance provide some measure of lactate tolerance and recovery adaptation training, even relatively short duration ext. tempo provides this mechanism, but generally aids in the recovery from more intense workouts while keeping volume high.