The literature suggests that interval running has a small but measurable benefit over and above continuous intensity running when it comes to eliciting improvements in VO2 Max – not only that but continuous intensity running around a track would be utterly tedious.
In order to build VO2 Max it seems there is little evidence that working above 80-85% of VO2 Max is during interval sets is actually worthwhile – and that the modest benefits of the 3-8 minute intervals can be gained at a ‘relatively’ low proportion of VO2 Max.
Therefore the ‘Four by 1200’ becomes quite a nice workout for the ‘mid pack’ athlete (if coaching athletes routinely doing sub 4-minutes for the 1200 I would suggest an alteration to use 4×1600). It is not too hard, but will maintain interest on the track and elicit VO2 Max gains.
The recovery between intervals should be ‘moving’ but doesn’t need to be at a particular intensity.
Bacon, A. P., Carter, R. E., Ogle, E. A., & Joyner, M. J. (2013). VO2max trainability and high intensity interval training in humans: a meta-analysis. PloS one, 8(9), e73182. https://doi.org/10.1371/journal.pone.0073182
Scribbans, T. D., Vecsey, S., Hankinson, P. B., Foster, W. S., & Gurd, B. J. (2016). The Effect of Training Intensity on VO2max in Young Healthy Adults: A Meta-Regression and Meta-Analysis. International journal of exercise science, 9(2), 230–247.
VO2max Trainability and High Intensity Interval Training in Humans: A Meta-Analysis
Bacon AP, Carter RE, Ogle EA, Joyner MJ (2013) VO2max Trainability and High Intensity Interval Training in Humans: A Meta-Analysis. PLOS ONE 8(9): e73182. https://doi.org/10.1371/journal.pone.0073182