Even at 11 miles or so each way I tend to get a second breakfast (though the first one is pretty small).

I think 36 each way would be doable (except in very foul weather), but you’d certainly have to work up to it and have the free time. When I was house shopping I wouldn’t have considered anything more than 20 miles, and 15 was my real sort of target max.

If you managed to work up to riding 36 miles each way every day, you’d be an absolute machine!