I did my first turbo session over 35 minutes today - 2 hour at 140bpm average (max 147)
Changed the cadence to various levels between 70 and 112rpm
Like many I had problems with my racing saddle so changed it to the glitter one I used for the 12h - much better
I found it gets easier after 45 minutes. At the 1h mark I found myself thinking "only an hour to go"
It's actually quite nice to be on the bike when you can hear the rain falling with the back door open
I am not sure I will be so fond of sessions at 160bpm and more ... we'll see ...