I do think it is a good way to work out, but not necessarily the best for triathletes, and in particular LC triathletes (only my opinion). I don't think I5 workouts combined with a lot of I1 work is the best way to go, as 1) you need to be pretty fresh in order to get quality into your I5 sessions and 2) the training load att high intensity will be way less than what you can achieve with a lot of workouts in I3. I believe that the muscular adaptations you get from I3 work is what is most important for triathletes as all disciplines are aerobic events, where increasing the lactate threshold is what will benefit you the most.

This is in accordance with Arild Tveiten`s philosophy (if I understand him correctly) and the way Olympiatoppen is heading. The idea is to keep the easy days easy (below 1.0mmol) and the hard days at the right intensity, which means at or below lactic threshold.