FWIW I just finished my first 3-week block of 9-11 hour/week FasCat sweet spot 2 and feel fine. It can be a fine line walking the 3:1 and 2:1 on/off schedule. Based on the past, I’m definitely going 2:1 when the vo2max work begins.
I’ve listened to Seiler and his position is that pro and elite training can be pushed down. I’m not of that opinion, for various reasons. My first point is that people respond differently as per the Alan Couzens’ “What type of athlete are you” blog post. And Mader’s research in the 80s led to training advances by Olbrecht (famous swimming coach) and Weber (INSCYD) that use Mader’s insights to tailor training based on individual responses to a block of training.
If Seiler is the Jay-Z of physiology as Fast Talk claims, I’d like to know which pro teams he is actively working with. Weber and INSCYD appear to be building success with some pro teams. Dismissing “the grey zone” and promoting what comes across as one-size-fits-all “polarized method” is more and more feeling like dogma.