Off-trail isn't fun. Everyone should stick to the trails where things are safe and predictable.
Are fire roads on or off trail?
My opinion (which self-admittedly means little....) is it's off the trail.
I voted 75%+ off trail by time but likely not by distance. Often where we go we may be off away from the trail most of the day but ultimately hook up with it and drive it back, plus to/from gas station and so on. So distance wise it's very possible some days may be better than 50% of the distance on the trail but 25% or less of the time is spent there.
Off-trail isn't fun. Everyone should stick to the trails where things are safe and predictable.