Treadmill workout

I've lost last months RW. There was a really brief workout for treadmill training. From memory it was: - 8 mins at marathon pace, 2 mins easy, then - 6 mins at half marathon pace, 4 mins easy, then - 4 mins at 10k pace, 6 mins easy, then - 2 mins at 5k pace, 8 mins easy But I think I've missed something, doesn't seem as long as I thought? Was it recommended to incorporate this into a weekly schedule? If anyone can remember I'd really appreciate clarification, many thanks.