Intervals twice a day! Should you? Could you? The truth about Norwegian Double Threshold

We have Norwegian Singles, Norwegian 4 x 4 but what started it all was the Norwegian Double Threshold Method.
Most people think it started with Jacob Ingebrigtsen but Norwegian 5,000 metre runner, Marius Bakken came up with it in the 1990s.
This video looks at the history, the obsessive testing by Bakken that formed what we now as the Norwegian Double Threshold System.
We break down each element and show a typical weeks training.
Could or should a non elite or a masters runner attempt it?
Or should they ‘water it down’ to the Norwegian Singles Method?