it seems to me the more immersive the platform the tougher it gets on the body. cheap vr gets on my nerves before i get queezy, a full on setup with peripherals and i feel like its a portal just getting back to irl.
I think the longest I've done in one go is about 3-4 hours. The weirdest part of VR for me was when I first got a headset, for about a week I felt like I was in VR all the time. The head-bobbing effect of walking in reality seemed exaggerated. But all that's faded away now. I can use VR without any adverse effects except maybe a bit of eye strain for a long session.