Thanks for your kind response, Scott and everyone. I reached out to Seiler who also recommended 1/3 of weekly total volume as a long EXTEND ride. So I am now riding 1.5 hours 4 days a week and one 3 hour ride for a total weekly volume of 9 hours (upped from the 8 hr/wk: 4-1hr-rides + the 4hr-long ride).
I was trying to scheme a way to increase to a weekly volume of twelve hours, and thats why I began contemplating two-in-a-day workouts and throwing in some short AeT workouts to extend my weekly volume.
But I’ve come to the conclusion that I am happy at 9 hours for now. So gone for now is my 4 hour AeT ride.
Btw, on another note, thanks for your articles that inspired me to purchase the Lactate Plus. I had successful first run.