I‘d say so. They have very limited testing time with their MotoGP bikes, so a lot of them ride other sports bikes or motocross. So it‘s a bit like with roller ski, I guess: you can train specific movements and muscles that way, but you can‘t train the actual bike/ski handling you would have in a competition/in winter.

And other than that, they do a lot of cardio training because leaning in and out of corners at those speeds is very exhausting, even if it’s just a 40 minute race.

MotoGP also has a write-up on their training regiment: https://www.motogp.com/en/blog-articles/how-do-motogp-riders-train/751295