This question actually made me sad…
Why do you ride to begin with? Are you a professional cyclist? Do you earn a majority of your living from racing? I’d ponder these questions.
If you have the opportunity to do a fun MTB ride in the real world and you’re willing to sacrifice that for a trainer day… I would seriously question your motivations.
Yes, a fast MTB ride will have MANY similar training benefits to a CX ride. Maybe the perfect trainer session could be superior physiologically, which I would seriously debate, as CX and MTB have a very significant skills component.
I love TrainerRoad, I love the podcast, I love the video content, but for crying out loud, some of the recent comments on trainer vs actual riding are getting well out of hand.
If you have the chance to get out into the world to ride your bike. Take it. Take it every single time. We do not have unlimited time on this Earth. I was recently asked what I valued an hour of my life at. Just a normal hour of your life. It had me seriously contemplating my choices on how I spend my time.
If you’re healthy and fortunate enough to be able to ride your sweet MTB, then ride it.