Rough-road seating is really about fatigue and risk distribution
On normal roads, the third row may feel only slightly less comfortable. On construction, washboard or gravel surfaces, the difference in vibration can become much more noticeable.
For mixed-age groups, that shift affects motion sickness, back strain and whether the group still has energy for the rest of the day.
Give the second row to the travellers who most need stability
The second row is usually better for people who are sensitive to jolts, already managing back discomfort, holding a child or handling the day's frequent support tasks. It is also easier for access and small repeated movements.
This is less about preference and more about preventing the most vulnerable travellers from being worn down first.
Use the third row for the members with the lightest load that day
Travellers who do not get motion sick easily, move well and are not responsible for frequent helping tasks are usually the best fit for the third row on a rough-road day.
The third row is not inherently wrong. It is simply the weaker choice for the people the group most needs to protect.
The strongest plan is to change seats with the road conditions
Many families lock the seats once at the start and stop thinking about them. On a Xinjiang route, though, smooth highways and rough scenic access roads can feel completely different.
If the difficult section starts later in the day, a temporary seat swap before it begins is often the most effective adjustment.