Checked out Dylan Johnson on youtube
@bobinski ..... flip he's dull! He may know his stuff, but I struggled to get through whole videos. Anyway, re the FTP video he did confirm that the workouts I'm doing (the 2x20 mins @ FTP) is a standard workout to improve your FTP (I've also got workouts for 3x15 mins which he also said was a standard workout)

Unfortunately he also re-iterated the need to mix hi-intensity with zone 2 rides so I'll need to learn to stick the trainer in zone 2 ERG mode and pootle and ignore the other riders coming past me
My main caveat to this guy is, whilst he quotes a lot of science, if you look at the articles he refers too, most of the time it's the same piece of research from 2010 (there may be more but I only saw that one pop up in multiple videos). The sceptic in me thinks he has found a piece of research that matches his own view and he'll keep pushing that one out. I'd have been more convinced by his arguments if he had quoted a wider source of research (as he's trying to prove his arguments are based on science).
Anyway, thanks for linking to him, he had a bit of interesting stuff to say, but I think I'll go back to GCN and Chris Pritchard as they're more my style of 'info-tainment'
Now, do I do an FTP workout later, or a zone 2 ride?