I played the final three hours of Half-Life: Alyx in a single session. Before Alyx, I never used VR for more than 30 minutes at a time. I don't get motion sick but I do get generally tired of VR. Tired of having a hunk of plastic strapped to my face, of having to stand and stoop and reach awkwardly around, of not being able to check my phone or have a sip of coffee. But I didn't take a break, or even want to, during the final chapters of Half-Life: Alyx. I wasn't tired. I was completely enthralled and unwilling to stop playing.
When I played through the ending (no spoilers here, but trust me, you'll want to keep your VR headset on through the credits), I reloaded my last autosave and played through the ending a second time. And then I went back to the beginning of the game and started playing again.